diff --git a/.php-cs-fixer.dist.php b/.php-cs-fixer.dist.php
index 958048f47..caae17b96 100644
--- a/.php-cs-fixer.dist.php
+++ b/.php-cs-fixer.dist.php
@@ -19,28 +19,6 @@ return (new Config())
         'phpdoc_types_order' => ['null_adjustment' => 'always_last', 'sort_algorithm' => 'none'],
         'no_superfluous_phpdoc_tags' => ['allow_mixed' => true, 'allow_unused_params' => true],
     ])
-    ->setRuleCustomisationPolicy(new class implements PhpCsFixer\Config\RuleCustomisationPolicyInterface {
-        public function getPolicyVersionForCache(): string
-        {
-            return hash_file('xxh128', __FILE__);
-        }
-
-        public function getRuleCustomisers(): array
-        {
-            return [
-                'void_return' => static function (SplFileInfo $file) {
-                    // temporary hack due to bug: https://github.com/symfony/symfony/issues/62734
-                    if (!$file instanceof Symfony\Component\Finder\SplFileInfo) {
-                        return false;
-                    }
-
-                    return !preg_match('#(^|/)tests/#i', $file->getRelativePathname());
-                },
-            ];
-        }
-    })
     ->setRiskyAllowed(true)
-    // the void_return customiser above is dropped by parallel workers, so run sequentially
-    ->setParallelConfig(ParallelConfigFactory::sequential())
     ->setFinder((new Finder())->in(__DIR__))
 ;
diff --git a/extra/cache-extra/Tests/FunctionalTest.php b/extra/cache-extra/Tests/FunctionalTest.php
index 31bf44971..97bf8cf83 100644
--- a/extra/cache-extra/Tests/FunctionalTest.php
+++ b/extra/cache-extra/Tests/FunctionalTest.php
@@ -23,7 +23,7 @@ use Twig\RuntimeLoader\RuntimeLoaderInterface;
 
 class FunctionalTest extends TestCase
 {
-    public function testIsCached()
+    public function testIsCached(): void
     {
         $cache = new ArrayAdapter();
         $twig = $this->createEnvironment(['index' => '{% cache "city;v1" %}{{- city -}}{% endcache %}'], $cache);
@@ -33,7 +33,7 @@ class FunctionalTest extends TestCase
         $this->assertSame('Paris', $value);
     }
 
-    public function testTtlNoArgs()
+    public function testTtlNoArgs(): void
     {
         $twig = $this->createEnvironment(['index' => '{% cache "ttl_no_args" ttl() %}{% endcache %}']);
         $this->expectException(SyntaxError::class);
@@ -41,7 +41,7 @@ class FunctionalTest extends TestCase
         $twig->render('index');
     }
 
-    public function testTtlTooManyArgs()
+    public function testTtlTooManyArgs(): void
     {
         $twig = $this->createEnvironment(['index' => '{% cache "ttl_too_many_args" ttl(0, 1) %}{% endcache %}']);
         $this->expectException(SyntaxError::class);
@@ -49,7 +49,7 @@ class FunctionalTest extends TestCase
         $twig->render('index');
     }
 
-    public function testTagsNoArgs()
+    public function testTagsNoArgs(): void
     {
         $twig = $this->createEnvironment(['index' => '{% cache "tags_no_args" tags() %}{% endcache %}']);
         $this->expectException(SyntaxError::class);
@@ -57,7 +57,7 @@ class FunctionalTest extends TestCase
         $twig->render('index');
     }
 
-    public function testTagsTooManyArgs()
+    public function testTagsTooManyArgs(): void
     {
         $twig = $this->createEnvironment(['index' => '{% cache "tags_too_many_args" tags(["foo"], 1) %}{% endcache %}']);
         $this->expectException(SyntaxError::class);
diff --git a/extra/cssinliner-extra/Tests/FunctionalTest.php b/extra/cssinliner-extra/Tests/FunctionalTest.php
index 72c152113..b93efd6a1 100644
--- a/extra/cssinliner-extra/Tests/FunctionalTest.php
+++ b/extra/cssinliner-extra/Tests/FunctionalTest.php
@@ -18,7 +18,7 @@ use Twig\Loader\ArrayLoader;
 
 class FunctionalTest extends TestCase
 {
-    public function testInlineCssIsNotSafeInJsContext()
+    public function testInlineCssIsNotSafeInJsContext(): void
     {
         $twig = new Environment(new ArrayLoader([
             'index' => "{% autoescape 'js' %}{% apply inline_css %}<p>x</p>{% endapply %}{% endautoescape %}",
@@ -32,7 +32,7 @@ class FunctionalTest extends TestCase
         $this->assertMatchesRegularExpression('{\\\\u003[Cc]p\\\\u003[Ee]x\\\\u003[Cc]\\\\/p\\\\u003[Ee]}', $output);
     }
 
-    public function testInlineCssPreEscapesUnsafeInput()
+    public function testInlineCssPreEscapesUnsafeInput(): void
     {
         $twig = new Environment(new ArrayLoader([
             'index' => '{{ payload|inline_css }}',
diff --git a/extra/cssinliner-extra/Tests/LegacyFunctionsTest.php b/extra/cssinliner-extra/Tests/LegacyFunctionsTest.php
index d62e267fd..4337f4e4f 100644
--- a/extra/cssinliner-extra/Tests/LegacyFunctionsTest.php
+++ b/extra/cssinliner-extra/Tests/LegacyFunctionsTest.php
@@ -21,7 +21,7 @@ use function Twig\Extra\CssInliner\twig_inline_css;
  */
 class LegacyFunctionsTest extends TestCase
 {
-    public function testInlineCss()
+    public function testInlineCss(): void
     {
         $this->assertSame(CssInlinerExtension::inlineCss('<p>body</p>', 'p { color: red }'), twig_inline_css('<p>body</p>', 'p { color: red }'));
     }
diff --git a/extra/html-extra/Tests/CvaTest.php b/extra/html-extra/Tests/CvaTest.php
index b8b32fbef..7f1e45660 100644
--- a/extra/html-extra/Tests/CvaTest.php
+++ b/extra/html-extra/Tests/CvaTest.php
@@ -19,14 +19,14 @@ class CvaTest extends TestCase
     /**
      * @dataProvider recipeProvider
      */
-    public function testRecipes(array $recipe, array $recipes, string $expected)
+    public function testRecipes(array $recipe, array $recipes, string $expected): void
     {
         $recipeClass = new Cva($recipe['base'] ?? '', $recipe['variants'] ?? [], $recipe['compounds'] ?? [], $recipe['defaultVariants'] ?? []);
 
         $this->assertEquals($expected, $recipeClass->apply($recipes));
     }
 
-    public function testApply()
+    public function testApply(): void
     {
         $recipe = new Cva('font-semibold border rounded', [
             'colors' => [
@@ -49,7 +49,7 @@ class CvaTest extends TestCase
         $this->assertEquals('font-semibold border rounded text-primary text-sm text-red-500', $recipe->apply(['colors' => 'primary', 'sizes' => 'sm']));
     }
 
-    public function testApplyWithNullString()
+    public function testApplyWithNullString(): void
     {
         $recipe = new Cva('font-semibold border rounded', [
             'colors' => [
@@ -623,7 +623,7 @@ class CvaTest extends TestCase
     /**
      * @dataProvider provideAdditionalClassesCases
      */
-    public function testAdditionalClasses(string|array $base, array|string $additionals, string $expected)
+    public function testAdditionalClasses(string|array $base, array|string $additionals, string $expected): void
     {
         $cva = new Cva($base);
         if (!$additionals) {
diff --git a/extra/html-extra/Tests/HtmlAttrMergeTest.php b/extra/html-extra/Tests/HtmlAttrMergeTest.php
index d129a5adf..6fa57911f 100644
--- a/extra/html-extra/Tests/HtmlAttrMergeTest.php
+++ b/extra/html-extra/Tests/HtmlAttrMergeTest.php
@@ -21,7 +21,7 @@ class HtmlAttrMergeTest extends TestCase
     /**
      * @dataProvider htmlAttrProvider
      */
-    public function testMerge(array $expected, array $inputs)
+    public function testMerge(array $expected, array $inputs): void
     {
         $result = HtmlExtension::htmlAttrMerge(...$inputs);
 
@@ -180,7 +180,7 @@ class HtmlAttrMergeTest extends TestCase
         ];
     }
 
-    public function testIncompatibleValuesMergeThrowsException()
+    public function testIncompatibleValuesMergeThrowsException(): void
     {
         $this->expectException(RuntimeError::class);
         $this->expectExceptionMessage('Cannot merge incompatible values for key "test"');
diff --git a/extra/html-extra/Tests/HtmlAttrTest.php b/extra/html-extra/Tests/HtmlAttrTest.php
index 13bd6694d..bbd7dbd97 100644
--- a/extra/html-extra/Tests/HtmlAttrTest.php
+++ b/extra/html-extra/Tests/HtmlAttrTest.php
@@ -24,7 +24,7 @@ class HtmlAttrTest extends TestCase
     /**
      * @dataProvider htmlAttrProvider
      */
-    public function testPrintingAttributes(string $expected, array $inputs)
+    public function testPrintingAttributes(string $expected, array $inputs): void
     {
         $result = HtmlExtension::htmlAttr(new Environment(new ArrayLoader()), ...$inputs);
 
@@ -285,7 +285,7 @@ class HtmlAttrTest extends TestCase
         ];
     }
 
-    public function testIterableObjectCastedToArray()
+    public function testIterableObjectCastedToArray(): void
     {
         /*
             This test case demonstrates how objects could e. g. implement helper logic
@@ -307,7 +307,7 @@ class HtmlAttrTest extends TestCase
         self::assertSame('data-controller="dropdown tooltip" data-action="click-&gt;dropdown#toggle mouseover-&gt;tooltip#show"', $result);
     }
 
-    public function testDataAttributeWithNonJsonEncodableValueThrowsRuntimeError()
+    public function testDataAttributeWithNonJsonEncodableValueThrowsRuntimeError(): void
     {
         $this->expectException(RuntimeError::class);
         $this->expectExceptionMessage('The "data-bad" attribute value cannot be JSON encoded.');
@@ -318,7 +318,7 @@ class HtmlAttrTest extends TestCase
         );
     }
 
-    public function testNonStringableObjectAsAttributeValueThrowsRuntimeError()
+    public function testNonStringableObjectAsAttributeValueThrowsRuntimeError(): void
     {
         $this->expectException(RuntimeError::class);
         $this->expectExceptionMessage('The "title" attribute value should be a scalar, an iterable, or an object implementing "Stringable"');
diff --git a/extra/html-extra/Tests/LegacyFunctionsTest.php b/extra/html-extra/Tests/LegacyFunctionsTest.php
index accf8afb3..3f961dad3 100644
--- a/extra/html-extra/Tests/LegacyFunctionsTest.php
+++ b/extra/html-extra/Tests/LegacyFunctionsTest.php
@@ -19,7 +19,7 @@ use Twig\Extra\Html\HtmlExtension;
  */
 class LegacyFunctionsTest extends TestCase
 {
-    public function testHtmlToMarkdown()
+    public function testHtmlToMarkdown(): void
     {
         $this->assertSame(HtmlExtension::htmlClasses(['charset' => 'utf-8']), twig_html_classes(['charset' => 'utf-8']));
     }
diff --git a/extra/inky-extra/Tests/FunctionalTest.php b/extra/inky-extra/Tests/FunctionalTest.php
index abf0c7194..4fbc8104f 100644
--- a/extra/inky-extra/Tests/FunctionalTest.php
+++ b/extra/inky-extra/Tests/FunctionalTest.php
@@ -18,7 +18,7 @@ use Twig\Loader\ArrayLoader;
 
 class FunctionalTest extends TestCase
 {
-    public function testInkyToHtmlPreEscapesUnsafeInput()
+    public function testInkyToHtmlPreEscapesUnsafeInput(): void
     {
         $twig = new Environment(new ArrayLoader([
             'index' => '{{ payload|inky_to_html }}',
diff --git a/extra/inky-extra/Tests/LegacyFunctionsTest.php b/extra/inky-extra/Tests/LegacyFunctionsTest.php
index 4810235b5..42d9c2923 100644
--- a/extra/inky-extra/Tests/LegacyFunctionsTest.php
+++ b/extra/inky-extra/Tests/LegacyFunctionsTest.php
@@ -21,7 +21,7 @@ use function Twig\Extra\Inky\twig_inky;
  */
 class LegacyFunctionsTest extends TestCase
 {
-    public function testInlineCss()
+    public function testInlineCss(): void
     {
         $this->assertSame(InkyExtension::inky('<p>Foo</p>'), twig_inky('<p>Foo</p>'));
     }
diff --git a/extra/intl-extra/Tests/IntlExtensionTest.php b/extra/intl-extra/Tests/IntlExtensionTest.php
index 403efbfa1..e870b7c4f 100644
--- a/extra/intl-extra/Tests/IntlExtensionTest.php
+++ b/extra/intl-extra/Tests/IntlExtensionTest.php
@@ -19,7 +19,7 @@ use Twig\Loader\ArrayLoader;
 
 class IntlExtensionTest extends TestCase
 {
-    public function testFormatterWithoutProto()
+    public function testFormatterWithoutProto(): void
     {
         $ext = new IntlExtension();
         $env = new Environment(new ArrayLoader());
@@ -31,7 +31,7 @@ class IntlExtensionTest extends TestCase
         );
     }
 
-    public function testFormatterWithoutProtoFallsBackToCoreExtensionTimezone()
+    public function testFormatterWithoutProtoFallsBackToCoreExtensionTimezone(): void
     {
         $ext = new IntlExtension();
         $env = new Environment(new ArrayLoader());
@@ -45,7 +45,7 @@ class IntlExtensionTest extends TestCase
         );
     }
 
-    public function testFormatterWithoutProtoSkipTimezoneConverter()
+    public function testFormatterWithoutProtoSkipTimezoneConverter(): void
     {
         $ext = new IntlExtension();
         $env = new Environment(new ArrayLoader());
@@ -59,7 +59,7 @@ class IntlExtensionTest extends TestCase
         );
     }
 
-    public function testFormatterProto()
+    public function testFormatterProto(): void
     {
         $dateFormatterProto = new \IntlDateFormatter('fr', \IntlDateFormatter::FULL, \IntlDateFormatter::FULL, new \DateTimeZone('Europe/Paris'));
         $numberFormatterProto = new \NumberFormatter('fr', \NumberFormatter::DECIMAL);
@@ -78,7 +78,7 @@ class IntlExtensionTest extends TestCase
         );
     }
 
-    public function testFormatterOverridenProto()
+    public function testFormatterOverridenProto(): void
     {
         $dateFormatterProto = new \IntlDateFormatter('fr', \IntlDateFormatter::FULL, \IntlDateFormatter::FULL, new \DateTimeZone('Europe/Paris'));
         $numberFormatterProto = new \NumberFormatter('fr', \NumberFormatter::DECIMAL);
@@ -97,7 +97,7 @@ class IntlExtensionTest extends TestCase
         );
     }
 
-    public function testDateFormatterCacheIsBounded()
+    public function testDateFormatterCacheIsBounded(): void
     {
         $ext = new IntlExtension();
         $env = new Environment(new ArrayLoader());
@@ -115,7 +115,7 @@ class IntlExtensionTest extends TestCase
         );
     }
 
-    public function testNumberFormatterCacheIsBounded()
+    public function testNumberFormatterCacheIsBounded(): void
     {
         $ext = new IntlExtension();
 
diff --git a/extra/markdown-extra/Tests/FunctionalTest.php b/extra/markdown-extra/Tests/FunctionalTest.php
index 9d5608253..863221d18 100644
--- a/extra/markdown-extra/Tests/FunctionalTest.php
+++ b/extra/markdown-extra/Tests/FunctionalTest.php
@@ -28,7 +28,7 @@ class FunctionalTest extends TestCase
     /**
      * @dataProvider getMarkdownTests
      */
-    public function testMarkdown(string $template, string $expected)
+    public function testMarkdown(string $template, string $expected): void
     {
         foreach ([LeagueMarkdown::class, ErusevMarkdown::class, /* MichelfMarkdown::class, */ DefaultMarkdown::class] as $class) {
             $twig = new Environment(new ArrayLoader([
@@ -92,7 +92,7 @@ EOF, "<p>Paragraph 1</p>\n+<p>Paragraph 2</p>"],
     /**
      * @dataProvider getIndentationTests
      */
-    public function testStripsCommonIndentation(string $body, string $expected)
+    public function testStripsCommonIndentation(string $body, string $expected): void
     {
         $runtime = new MarkdownRuntime(new class implements MarkdownInterface {
             public function convert(string $body): string
@@ -117,7 +117,7 @@ EOF, "<p>Paragraph 1</p>\n+<p>Paragraph 2</p>"],
         ];
     }
 
-    public function testMarkdownToHtmlIsNotSafeInJsContext()
+    public function testMarkdownToHtmlIsNotSafeInJsContext(): void
     {
         $twig = new Environment(new ArrayLoader([
             'index' => "{% autoescape 'js' %}{{ '# Hello'|markdown_to_html }}{% endautoescape %}",
diff --git a/extra/markdown-extra/Tests/LegacyFunctionsTest.php b/extra/markdown-extra/Tests/LegacyFunctionsTest.php
index 19a861de3..5fb5ed360 100644
--- a/extra/markdown-extra/Tests/LegacyFunctionsTest.php
+++ b/extra/markdown-extra/Tests/LegacyFunctionsTest.php
@@ -22,7 +22,7 @@ use Twig\Extra\Markdown\MarkdownExtension;
  */
 class LegacyFunctionsTest extends TestCase
 {
-    public function testHtmlToMarkdown()
+    public function testHtmlToMarkdown(): void
     {
         $this->assertSame(MarkdownExtension::htmlToMarkdown('<p>foo</p>'), html_to_markdown('<p>foo</p>'));
     }
diff --git a/extra/twig-extra-bundle/DependencyInjection/Compiler/MissingExtensionSuggestorPass.php b/extra/twig-extra-bundle/DependencyInjection/Compiler/MissingExtensionSuggestorPass.php
index fdd65820b..7833336bc 100644
--- a/extra/twig-extra-bundle/DependencyInjection/Compiler/MissingExtensionSuggestorPass.php
+++ b/extra/twig-extra-bundle/DependencyInjection/Compiler/MissingExtensionSuggestorPass.php
@@ -34,8 +34,7 @@ if (!method_exists(ContainerBuilder::class, 'getAutoconfiguredAttributes')) {
 } else {
     class MissingExtensionSuggestorPass implements CompilerPassInterface
     {
-        /** @return void */
-        public function process(ContainerBuilder $container)
+        public function process(ContainerBuilder $container): void
         {
             if (!$container->getParameter('kernel.debug')) {
                 return;
diff --git a/extra/twig-extra-bundle/DependencyInjection/TwigExtraExtension.php b/extra/twig-extra-bundle/DependencyInjection/TwigExtraExtension.php
index b7f732f90..6de993717 100644
--- a/extra/twig-extra-bundle/DependencyInjection/TwigExtraExtension.php
+++ b/extra/twig-extra-bundle/DependencyInjection/TwigExtraExtension.php
@@ -31,8 +31,7 @@ if (!method_exists(ContainerBuilder::class, 'getAutoconfiguredAttributes')) {
     /** @internal */
     trait TwigExtraExtensionTrait
     {
-        /** @return void */
-        public function load(array $configs, ContainerBuilder $container)
+        public function load(array $configs, ContainerBuilder $container): void
         {
             $this->doLoad($configs, $container);
         }
diff --git a/extra/twig-extra-bundle/Tests/DependencyInjection/TwigExtraExtensionTest.php b/extra/twig-extra-bundle/Tests/DependencyInjection/TwigExtraExtensionTest.php
index ce263ac2c..177c6acd3 100644
--- a/extra/twig-extra-bundle/Tests/DependencyInjection/TwigExtraExtensionTest.php
+++ b/extra/twig-extra-bundle/Tests/DependencyInjection/TwigExtraExtensionTest.php
@@ -20,7 +20,7 @@ use Twig\Extra\TwigExtraBundle\Extensions;
 
 class TwigExtraExtensionTest extends TestCase
 {
-    public function testDefaultConfiguration()
+    public function testDefaultConfiguration(): void
     {
         $container = new ContainerBuilder(new ParameterBag([
             'kernel.debug' => false,
diff --git a/extra/twig-extra-bundle/Tests/IntegrationTest.php b/extra/twig-extra-bundle/Tests/IntegrationTest.php
index df62da2da..3d22851c5 100644
--- a/extra/twig-extra-bundle/Tests/IntegrationTest.php
+++ b/extra/twig-extra-bundle/Tests/IntegrationTest.php
@@ -15,7 +15,7 @@ use Symfony\Bundle\FrameworkBundle\Test\KernelTestCase;
 
 class IntegrationTest extends KernelTestCase
 {
-    public function testCommonMarkRendering()
+    public function testCommonMarkRendering(): void
     {
         self::bootKernel();
 
diff --git a/extra/twig-extra-bundle/TwigExtraBundle.php b/extra/twig-extra-bundle/TwigExtraBundle.php
index 495785623..5289e1feb 100644
--- a/extra/twig-extra-bundle/TwigExtraBundle.php
+++ b/extra/twig-extra-bundle/TwigExtraBundle.php
@@ -29,8 +29,7 @@ if (method_exists(KernelInterface::class, 'getShareDir')) {
 } else {
     class TwigExtraBundle extends Bundle
     {
-        /** @return void */
-        public function build(ContainerBuilder $container)
+        public function build(ContainerBuilder $container): void
         {
             parent::build($container);
 
diff --git a/src/Environment.php b/src/Environment.php
index 71459e210..2d75b0b0a 100644
--- a/src/Environment.php
+++ b/src/Environment.php
@@ -157,7 +157,7 @@ class Environment
      *
      * @return void
      */
-    public function enableDebug()
+    public function enableDebug(): void
     {
         $this->debug = true;
         $this->updateOptionsHash();
@@ -168,7 +168,7 @@ class Environment
      *
      * @return void
      */
-    public function disableDebug()
+    public function disableDebug(): void
     {
         $this->debug = false;
         $this->updateOptionsHash();
@@ -189,7 +189,7 @@ class Environment
      *
      * @return void
      */
-    public function enableAutoReload()
+    public function enableAutoReload(): void
     {
         $this->autoReload = true;
     }
@@ -199,7 +199,7 @@ class Environment
      *
      * @return void
      */
-    public function disableAutoReload()
+    public function disableAutoReload(): void
     {
         $this->autoReload = false;
     }
@@ -219,7 +219,7 @@ class Environment
      *
      * @return void
      */
-    public function enableStrictVariables()
+    public function enableStrictVariables(): void
     {
         $this->strictVariables = true;
         $this->updateOptionsHash();
@@ -230,7 +230,7 @@ class Environment
      *
      * @return void
      */
-    public function disableStrictVariables()
+    public function disableStrictVariables(): void
     {
         $this->strictVariables = false;
         $this->updateOptionsHash();
@@ -281,7 +281,7 @@ class Environment
      *
      * @return void
      */
-    public function setCache($cache)
+    public function setCache($cache): void
     {
         if (\is_string($cache)) {
             $this->originalCache = $cache;
@@ -519,7 +519,7 @@ class Environment
     /**
      * @return void
      */
-    public function setLexer(Lexer $lexer)
+    public function setLexer(Lexer $lexer): void
     {
         $this->lexer = $lexer;
     }
@@ -539,7 +539,7 @@ class Environment
     /**
      * @return void
      */
-    public function setParser(Parser $parser)
+    public function setParser(Parser $parser): void
     {
         $this->parser = $parser;
     }
@@ -561,7 +561,7 @@ class Environment
     /**
      * @return void
      */
-    public function setCompiler(Compiler $compiler)
+    public function setCompiler(Compiler $compiler): void
     {
         $this->compiler = $compiler;
     }
@@ -598,7 +598,7 @@ class Environment
     /**
      * @return void
      */
-    public function setLoader(LoaderInterface $loader)
+    public function setLoader(LoaderInterface $loader): void
     {
         $this->loader = $loader;
     }
@@ -611,7 +611,7 @@ class Environment
     /**
      * @return void
      */
-    public function setCharset(string $charset)
+    public function setCharset(string $charset): void
     {
         if ('UTF8' === $charset = strtoupper($charset ?: '')) {
             // iconv on Windows requires "UTF-8" instead of "UTF8"
@@ -634,7 +634,7 @@ class Environment
     /**
      * @return void
      */
-    public function addRuntimeLoader(RuntimeLoaderInterface $loader)
+    public function addRuntimeLoader(RuntimeLoaderInterface $loader): void
     {
         $this->runtimeLoaders[] = $loader;
     }
@@ -684,7 +684,7 @@ class Environment
     /**
      * @return void
      */
-    public function addExtension(ExtensionInterface $extension)
+    public function addExtension(ExtensionInterface $extension): void
     {
         $this->extensionSet->addExtension($extension);
         $this->updateOptionsHash();
@@ -695,7 +695,7 @@ class Environment
      *
      * @return void
      */
-    public function setExtensions(array $extensions)
+    public function setExtensions(array $extensions): void
     {
         $this->extensionSet->setExtensions($extensions);
         $this->updateOptionsHash();
@@ -712,7 +712,7 @@ class Environment
     /**
      * @return void
      */
-    public function addTokenParser(TokenParserInterface $parser)
+    public function addTokenParser(TokenParserInterface $parser): void
     {
         $this->extensionSet->addTokenParser($parser);
     }
@@ -746,7 +746,7 @@ class Environment
     /**
      * @return void
      */
-    public function addNodeVisitor(NodeVisitorInterface $visitor)
+    public function addNodeVisitor(NodeVisitorInterface $visitor): void
     {
         $this->extensionSet->addNodeVisitor($visitor);
     }
@@ -764,7 +764,7 @@ class Environment
     /**
      * @return void
      */
-    public function addFilter(TwigFilter $filter)
+    public function addFilter(TwigFilter $filter): void
     {
         $this->extensionSet->addFilter($filter);
     }
@@ -804,7 +804,7 @@ class Environment
     /**
      * @return void
      */
-    public function addTest(TwigTest $test)
+    public function addTest(TwigTest $test): void
     {
         $this->extensionSet->addTest($test);
     }
@@ -838,7 +838,7 @@ class Environment
     /**
      * @return void
      */
-    public function addFunction(TwigFunction $function)
+    public function addFunction(TwigFunction $function): void
     {
         $this->extensionSet->addFunction($function);
     }
@@ -885,7 +885,7 @@ class Environment
      *
      * @return void
      */
-    public function addGlobal(string $name, $value)
+    public function addGlobal(string $name, $value): void
     {
         if ($this->extensionSet->isInitialized() && !\array_key_exists($name, $this->getGlobals())) {
             throw new \LogicException(\sprintf('Unable to add global "%s" as the runtime or the extensions have already been initialized.', $name));
diff --git a/src/Extension/CoreExtension.php b/src/Extension/CoreExtension.php
index 9ef620b6a..e299f1dc6 100644
--- a/src/Extension/CoreExtension.php
+++ b/src/Extension/CoreExtension.php
@@ -143,7 +143,7 @@ final class CoreExtension extends AbstractExtension
      * @param string|null $format             The default date format string
      * @param string|null $dateIntervalFormat The default date interval format string
      */
-    public function setDateFormat($format = null, $dateIntervalFormat = null)
+    public function setDateFormat($format = null, $dateIntervalFormat = null): void
     {
         if (null !== $format) {
             $this->dateFormats[0] = $format;
@@ -169,7 +169,7 @@ final class CoreExtension extends AbstractExtension
      *
      * @param \DateTimeZone|string $timezone The default timezone string or a \DateTimeZone object
      */
-    public function setTimezone($timezone)
+    public function setTimezone($timezone): void
     {
         $this->timezone = $timezone instanceof \DateTimeZone ? $timezone : new \DateTimeZone($timezone);
     }
@@ -195,7 +195,7 @@ final class CoreExtension extends AbstractExtension
      * @param string $decimalPoint the character(s) to use for the decimal point
      * @param string $thousandSep  the character(s) to use for the thousands separator
      */
-    public function setNumberFormat($decimal, $decimalPoint, $thousandSep)
+    public function setNumberFormat($decimal, $decimalPoint, $thousandSep): void
     {
         $this->numberFormat = [$decimal, $decimalPoint, $thousandSep];
     }
@@ -2115,7 +2115,7 @@ final class CoreExtension extends AbstractExtension
     /**
      * @internal
      */
-    public static function checkArrow(bool $isSandboxed, $arrow, $thing, $type)
+    public static function checkArrow(bool $isSandboxed, $arrow, $thing, $type): void
     {
         if ($arrow instanceof \Closure) {
             return;
diff --git a/src/Extension/EscaperExtension.php b/src/Extension/EscaperExtension.php
index 6d9d1ce24..f666e3fdb 100644
--- a/src/Extension/EscaperExtension.php
+++ b/src/Extension/EscaperExtension.php
@@ -80,11 +80,9 @@ final class EscaperExtension extends AbstractExtension
     }
 
     /**
-     * @return void
-     *
      * @deprecated since Twig 3.10
      */
-    public function setEscaperRuntime(EscaperRuntime $escaper)
+    public function setEscaperRuntime(EscaperRuntime $escaper): void
     {
         trigger_deprecation('twig/twig', '3.10', 'The "%s()" method is deprecated and not needed if you are using methods from "Twig\Runtime\EscaperRuntime".', __METHOD__);
 
@@ -132,11 +130,9 @@ final class EscaperExtension extends AbstractExtension
      * @param string                                        $strategy The strategy name that should be used as a strategy in the escape call
      * @param callable(Environment, string, string): string $callable A valid PHP callable
      *
-     * @return void
-     *
      * @deprecated since Twig 3.10
      */
-    public function setEscaper($strategy, callable $callable)
+    public function setEscaper($strategy, callable $callable): void
     {
         trigger_deprecation('twig/twig', '3.10', 'The "%s()" method is deprecated, use the "Twig\Runtime\EscaperRuntime::setEscaper()" method instead (be warned that Environment is not passed anymore to the callable).', __METHOD__);
 
@@ -165,11 +161,9 @@ final class EscaperExtension extends AbstractExtension
     }
 
     /**
-     * @return void
-     *
      * @deprecated since Twig 3.10
      */
-    public function setSafeClasses(array $safeClasses = [])
+    public function setSafeClasses(array $safeClasses = []): void
     {
         trigger_deprecation('twig/twig', '3.10', 'The "%s()" method is deprecated, use the "Twig\Runtime\EscaperRuntime::setSafeClasses()" method instead.', __METHOD__);
 
@@ -177,11 +171,9 @@ final class EscaperExtension extends AbstractExtension
     }
 
     /**
-     * @return void
-     *
      * @deprecated since Twig 3.10
      */
-    public function addSafeClass(string $class, array $strategies)
+    public function addSafeClass(string $class, array $strategies): void
     {
         trigger_deprecation('twig/twig', '3.10', 'The "%s()" method is deprecated, use the "Twig\Runtime\EscaperRuntime::addSafeClass()" method instead.', __METHOD__);
 
diff --git a/src/Extension/ProfilerExtension.php b/src/Extension/ProfilerExtension.php
index 43e4a449e..b3ad42cc8 100644
--- a/src/Extension/ProfilerExtension.php
+++ b/src/Extension/ProfilerExtension.php
@@ -23,19 +23,13 @@ class ProfilerExtension extends AbstractExtension
         $this->actives[] = $profile;
     }
 
-    /**
-     * @return void
-     */
-    public function enter(Profile $profile)
+    public function enter(Profile $profile): void
     {
         $this->actives[0]->addProfile($profile);
         array_unshift($this->actives, $profile);
     }
 
-    /**
-     * @return void
-     */
-    public function leave(Profile $profile)
+    public function leave(Profile $profile): void
     {
         $profile->leave();
         array_shift($this->actives);
diff --git a/src/ExtensionSet.php b/src/ExtensionSet.php
index 7bb62fa78..aa5568986 100644
--- a/src/ExtensionSet.php
+++ b/src/ExtensionSet.php
@@ -77,7 +77,7 @@ final class ExtensionSet
     /**
      * @return void
      */
-    public function initRuntime()
+    public function initRuntime(): void
     {
         $this->runtimeInitialized = true;
     }
diff --git a/src/Node/CheckSecurityCallNode.php b/src/Node/CheckSecurityCallNode.php
index 0667bd0fd..978e54ca3 100644
--- a/src/Node/CheckSecurityCallNode.php
+++ b/src/Node/CheckSecurityCallNode.php
@@ -23,7 +23,7 @@ class CheckSecurityCallNode extends Node
     /**
      * @return void
      */
-    public function compile(Compiler $compiler)
+    public function compile(Compiler $compiler): void
     {
         $compiler
             ->write("\$this->sandbox = \$this->extensions[SandboxExtension::class];\n")
diff --git a/src/Node/Expression/CallExpression.php b/src/Node/Expression/CallExpression.php
index ad6d3881a..fdebb6ec3 100644
--- a/src/Node/Expression/CallExpression.php
+++ b/src/Node/Expression/CallExpression.php
@@ -29,7 +29,7 @@ abstract class CallExpression extends AbstractExpression
     /**
      * @return void
      */
-    protected function compileCallable(Compiler $compiler)
+    protected function compileCallable(Compiler $compiler): void
     {
         $twigCallable = $this->getTwigCallable();
         $callable = $twigCallable->getCallable();
diff --git a/src/Node/Expression/FunctionExpression.php b/src/Node/Expression/FunctionExpression.php
index 5983962dc..179dd2070 100644
--- a/src/Node/Expression/FunctionExpression.php
+++ b/src/Node/Expression/FunctionExpression.php
@@ -58,7 +58,7 @@ class FunctionExpression extends CallExpression implements SupportDefinedTestInt
     /**
      * @return void
      */
-    public function compile(Compiler $compiler)
+    public function compile(Compiler $compiler): void
     {
         $name = $this->getAttribute('name');
         if ($this->hasAttribute('twig_callable')) {
diff --git a/src/Node/IncludeNode.php b/src/Node/IncludeNode.php
index 3adf415e1..6e46e481e 100644
--- a/src/Node/IncludeNode.php
+++ b/src/Node/IncludeNode.php
@@ -82,7 +82,7 @@ class IncludeNode extends Node implements NodeOutputInterface, CoercesChildrenTo
     /**
      * @return void
      */
-    protected function addGetTemplate(Compiler $compiler/* , string $template = '' */)
+    protected function addGetTemplate(Compiler $compiler/* , string $template = '' */): void
     {
         $compiler
             ->raw('$this->load(')
@@ -96,7 +96,7 @@ class IncludeNode extends Node implements NodeOutputInterface, CoercesChildrenTo
     /**
      * @return void
      */
-    protected function addTemplateArguments(Compiler $compiler)
+    protected function addTemplateArguments(Compiler $compiler): void
     {
         if (!$this->hasNode('variables')) {
             $compiler->raw(false === $this->getAttribute('only') ? '$context' : '[]');
diff --git a/src/Node/ModuleNode.php b/src/Node/ModuleNode.php
index fd43246f4..13d81c8cd 100644
--- a/src/Node/ModuleNode.php
+++ b/src/Node/ModuleNode.php
@@ -76,7 +76,7 @@ final class ModuleNode extends Node implements CoercesChildrenToStringInterface
     /**
      * @return void
      */
-    public function setIndex($index)
+    public function setIndex($index): void
     {
         $this->setAttribute('index', $index);
     }
@@ -99,7 +99,7 @@ final class ModuleNode extends Node implements CoercesChildrenToStringInterface
     /**
      * @return void
      */
-    protected function compileTemplate(Compiler $compiler)
+    protected function compileTemplate(Compiler $compiler): void
     {
         if (!$this->getAttribute('index')) {
             $compiler->write('<?php');
@@ -131,7 +131,7 @@ final class ModuleNode extends Node implements CoercesChildrenToStringInterface
     /**
      * @return void
      */
-    protected function compileGetParent(Compiler $compiler)
+    protected function compileGetParent(Compiler $compiler): void
     {
         if (!$this->hasNode('parent')) {
             return;
@@ -167,7 +167,7 @@ final class ModuleNode extends Node implements CoercesChildrenToStringInterface
     /**
      * @return void
      */
-    protected function compileClassHeader(Compiler $compiler)
+    protected function compileClassHeader(Compiler $compiler): void
     {
         $compiler
             ->write("\n\n")
@@ -209,7 +209,7 @@ final class ModuleNode extends Node implements CoercesChildrenToStringInterface
     /**
      * @return void
      */
-    protected function compileConstructor(Compiler $compiler)
+    protected function compileConstructor(Compiler $compiler): void
     {
         $compiler
             ->write("public function __construct(Environment \$env)\n", "{\n")
@@ -349,7 +349,7 @@ final class ModuleNode extends Node implements CoercesChildrenToStringInterface
     /**
      * @return void
      */
-    protected function compileDisplay(Compiler $compiler)
+    protected function compileDisplay(Compiler $compiler): void
     {
         $compiler
             ->write("protected function doDisplay(array \$context, array \$blocks = []): iterable\n", "{\n")
@@ -397,7 +397,7 @@ final class ModuleNode extends Node implements CoercesChildrenToStringInterface
     /**
      * @return void
      */
-    protected function compileClassFooter(Compiler $compiler)
+    protected function compileClassFooter(Compiler $compiler): void
     {
         $compiler
             ->subcompile($this->getNode('class_end'))
@@ -409,7 +409,7 @@ final class ModuleNode extends Node implements CoercesChildrenToStringInterface
     /**
      * @return void
      */
-    protected function compileMacros(Compiler $compiler)
+    protected function compileMacros(Compiler $compiler): void
     {
         $compiler->subcompile($this->getNode('macros'));
     }
@@ -417,7 +417,7 @@ final class ModuleNode extends Node implements CoercesChildrenToStringInterface
     /**
      * @return void
      */
-    protected function compileGetTemplateName(Compiler $compiler)
+    protected function compileGetTemplateName(Compiler $compiler): void
     {
         $compiler
             ->write("/**\n")
@@ -436,7 +436,7 @@ final class ModuleNode extends Node implements CoercesChildrenToStringInterface
     /**
      * @return void
      */
-    protected function compileIsTraitable(Compiler $compiler)
+    protected function compileIsTraitable(Compiler $compiler): void
     {
         // A template can be used as a trait if:
         //   * it has no parent
@@ -486,7 +486,7 @@ final class ModuleNode extends Node implements CoercesChildrenToStringInterface
     /**
      * @return void
      */
-    protected function compileDebugInfo(Compiler $compiler)
+    protected function compileDebugInfo(Compiler $compiler): void
     {
         $compiler
             ->write("/**\n")
@@ -503,7 +503,7 @@ final class ModuleNode extends Node implements CoercesChildrenToStringInterface
     /**
      * @return void
      */
-    protected function compileGetSourceContext(Compiler $compiler)
+    protected function compileGetSourceContext(Compiler $compiler): void
     {
         $compiler
             ->write("public function getSourceContext(): Source\n", "{\n")
diff --git a/src/Node/Node.php b/src/Node/Node.php
index dcf912c21..574067475 100644
--- a/src/Node/Node.php
+++ b/src/Node/Node.php
@@ -115,7 +115,7 @@ class Node implements \Countable, \IteratorAggregate
     /**
      * @return void
      */
-    public function compile(Compiler $compiler)
+    public function compile(Compiler $compiler): void
     {
         foreach ($this->nodes as $node) {
             $compiler->subcompile($node);
diff --git a/src/Node/TypesNode.php b/src/Node/TypesNode.php
index a18288083..f933b923d 100644
--- a/src/Node/TypesNode.php
+++ b/src/Node/TypesNode.php
@@ -33,7 +33,7 @@ class TypesNode extends Node
     /**
      * @return void
      */
-    public function compile(Compiler $compiler)
+    public function compile(Compiler $compiler): void
     {
         // Don't compile anything.
     }
diff --git a/src/Parser.php b/src/Parser.php
index 5ef1aea8d..7d5b223ab 100644
--- a/src/Parser.php
+++ b/src/Parser.php
@@ -321,7 +321,7 @@ class Parser
     /**
      * @return void
      */
-    public function embedTemplate(ModuleNode $template)
+    public function embedTemplate(ModuleNode $template): void
     {
         $template->setIndex(++$this->lastEmbedIndex);
 
@@ -571,7 +571,7 @@ class Parser
         return $body;
     }
 
-    private function checkPrecedenceDeprecations(ExpressionParserInterface $expressionParser, AbstractExpression $expr)
+    private function checkPrecedenceDeprecations(ExpressionParserInterface $expressionParser, AbstractExpression $expr): void
     {
         $this->expressionRefs[$expr] = $expressionParser;
         $precedenceChanges = $this->parsers->getPrecedenceChanges();
diff --git a/src/Resources/core.php b/src/Resources/core.php
index 80f62cf69..df143d9e9 100644
--- a/src/Resources/core.php
+++ b/src/Resources/core.php
@@ -536,7 +536,7 @@ function twig_array_every(Environment $env, $array, $arrow)
  *
  * @deprecated since Twig 3.9
  */
-function twig_check_arrow_in_sandbox(Environment $env, $arrow, $thing, $type)
+function twig_check_arrow_in_sandbox(Environment $env, $arrow, $thing, $type): void
 {
     trigger_deprecation('twig/twig', '3.9', 'Using the internal "%s" function is deprecated.', __FUNCTION__);
 
diff --git a/src/Resources/debug.php b/src/Resources/debug.php
index a0392ff51..0fd6c7b08 100644
--- a/src/Resources/debug.php
+++ b/src/Resources/debug.php
@@ -17,7 +17,7 @@ use Twig\Extension\DebugExtension;
  *
  * @deprecated since Twig 3.9
  */
-function twig_var_dump(Environment $env, $context, ...$vars)
+function twig_var_dump(Environment $env, $context, ...$vars): void
 {
     trigger_deprecation('twig/twig', '3.9', 'Using the internal "%s" function is deprecated.', __FUNCTION__);
 
diff --git a/src/Runtime/EscaperRuntime.php b/src/Runtime/EscaperRuntime.php
index f4a7023c7..57f116680 100644
--- a/src/Runtime/EscaperRuntime.php
+++ b/src/Runtime/EscaperRuntime.php
@@ -39,7 +39,7 @@ final class EscaperRuntime implements RuntimeExtensionInterface
      *
      * @return void
      */
-    public function setEscaper($strategy, callable $callable)
+    public function setEscaper($strategy, callable $callable): void
     {
         $this->escapers[$strategy] = $callable;
     }
@@ -59,7 +59,7 @@ final class EscaperRuntime implements RuntimeExtensionInterface
      *
      * @return void
      */
-    public function setSafeClasses(array $safeClasses = [])
+    public function setSafeClasses(array $safeClasses = []): void
     {
         $this->safeClasses = [];
         $this->safeLookup = [];
@@ -74,7 +74,7 @@ final class EscaperRuntime implements RuntimeExtensionInterface
      *
      * @return void
      */
-    public function addSafeClass(string $class, array $strategies)
+    public function addSafeClass(string $class, array $strategies): void
     {
         $class = ltrim($class, '\\');
         if (!isset($this->safeClasses[$class])) {
diff --git a/src/TemplateWrapper.php b/src/TemplateWrapper.php
index 265ce3e1c..e0ce7a51d 100644
--- a/src/TemplateWrapper.php
+++ b/src/TemplateWrapper.php
@@ -54,7 +54,7 @@ final class TemplateWrapper
     /**
      * @return void
      */
-    public function display(array $context = [])
+    public function display(array $context = []): void
     {
         // using func_get_args() allows to not expose the blocks argument
         // as it should only be used by internal code
@@ -82,7 +82,7 @@ final class TemplateWrapper
     /**
      * @return void
      */
-    public function displayBlock(string $name, array $context = [])
+    public function displayBlock(string $name, array $context = []): void
     {
         $context += $this->env->getGlobals();
         foreach ($this->template->yieldBlock($name, $context) as $data) {
diff --git a/src/Test/IntegrationTestCase.php b/src/Test/IntegrationTestCase.php
index 749174bdd..c66f4783e 100644
--- a/src/Test/IntegrationTestCase.php
+++ b/src/Test/IntegrationTestCase.php
@@ -127,7 +127,7 @@ abstract class IntegrationTestCase extends TestCase
      * @return void
      */
     #[DataProvider('provideTests')]
-    public function testIntegration($file, $message, $condition, $templates, $exception, $outputs, $deprecation = '')
+    public function testIntegration($file, $message, $condition, $templates, $exception, $outputs, $deprecation = ''): void
     {
         $this->doIntegrationTest($file, $message, $condition, $templates, $exception, $outputs, $deprecation);
     }
@@ -140,7 +140,7 @@ abstract class IntegrationTestCase extends TestCase
      * @return void
      */
     #[DataProvider('provideLegacyTests'), Group('legacy')]
-    public function testLegacyIntegration($file, $message, $condition, $templates, $exception, $outputs, $deprecation = '')
+    public function testLegacyIntegration($file, $message, $condition, $templates, $exception, $outputs, $deprecation = ''): void
     {
         $this->doIntegrationTest($file, $message, $condition, $templates, $exception, $outputs, $deprecation);
     }
@@ -230,7 +230,7 @@ abstract class IntegrationTestCase extends TestCase
     /**
      * @return void
      */
-    protected function doIntegrationTest($file, $message, $condition, $templateSources, $exception, $outputs, $deprecation = '')
+    protected function doIntegrationTest($file, $message, $condition, $templateSources, $exception, $outputs, $deprecation = ''): void
     {
         if (!$outputs) {
             // dummy test added by assembleTests() when there is no (legacy) test to run
diff --git a/src/Test/NodeTestCase.php b/src/Test/NodeTestCase.php
index 3ce58b3bf..39dd3b1ec 100644
--- a/src/Test/NodeTestCase.php
+++ b/src/Test/NodeTestCase.php
@@ -53,7 +53,7 @@ abstract class NodeTestCase extends TestCase
      * @return void
      */
     #[DataProvider('provideTests')]
-    public function testCompile($node, $source, $environment = null, $isPattern = false)
+    public function testCompile($node, $source, $environment = null, $isPattern = false): void
     {
         $this->assertNodeCompilation($source, $node, $environment, $isPattern);
     }
@@ -61,7 +61,7 @@ abstract class NodeTestCase extends TestCase
     /**
      * @return void
      */
-    public function assertNodeCompilation($source, Node $node, ?Environment $environment = null, $isPattern = false)
+    public function assertNodeCompilation($source, Node $node, ?Environment $environment = null, $isPattern = false): void
     {
         $compiler = $this->getCompiler($environment);
         $compiler->compile($node);
diff --git a/src/TokenStream.php b/src/TokenStream.php
index 2586750fa..d9804e320 100644
--- a/src/TokenStream.php
+++ b/src/TokenStream.php
@@ -42,7 +42,7 @@ final class TokenStream
     /**
      * @return void
      */
-    public function injectTokens(array $tokens)
+    public function injectTokens(array $tokens): void
     {
         $this->tokens = array_merge(\array_slice($this->tokens, 0, $this->current), $tokens, \array_slice($this->tokens, $this->current));
     }
diff --git a/tests/Cache/ChainTest.php b/tests/Cache/ChainTest.php
index a14aa4c85..3a57a5212 100644
--- a/tests/Cache/ChainTest.php
+++ b/tests/Cache/ChainTest.php
@@ -52,7 +52,7 @@ class ChainTest extends TestCase
         }
     }
 
-    public function testLoadInA()
+    public function testLoadInA(): void
     {
         $cache = new FilesystemCache($this->directory.'/A');
         $key = $cache->generateKey('_test_', $this->className);
@@ -70,7 +70,7 @@ class ChainTest extends TestCase
         $this->assertTrue(class_exists($this->className, false));
     }
 
-    public function testLoadInB()
+    public function testLoadInB(): void
     {
         $cache = new FilesystemCache($this->directory.'/B');
         $key = $cache->generateKey('_test_', $this->className);
@@ -88,7 +88,7 @@ class ChainTest extends TestCase
         $this->assertTrue(class_exists($this->className, false));
     }
 
-    public function testLoadInBoth()
+    public function testLoadInBoth(): void
     {
         $cache = new FilesystemCache($this->directory.'/A');
         $key = $cache->generateKey('_test_', $this->className);
@@ -117,7 +117,7 @@ class ChainTest extends TestCase
         $this->assertTrue(class_exists($this->className, false));
     }
 
-    public function testLoadMissing()
+    public function testLoadMissing(): void
     {
         $this->assertFalse(class_exists($this->className, false));
 
@@ -126,7 +126,7 @@ class ChainTest extends TestCase
         $this->assertFalse(class_exists($this->className, false));
     }
 
-    public function testWrite()
+    public function testWrite(): void
     {
         $content = $this->generateSource();
 
@@ -153,7 +153,7 @@ class ChainTest extends TestCase
         $this->assertSame(file_get_contents($keyB), $content);
     }
 
-    public function testGetTimestampInA()
+    public function testGetTimestampInA(): void
     {
         $cache = new FilesystemCache($this->directory.'/A');
         $key = $cache->generateKey('_test_', $this->className);
@@ -168,7 +168,7 @@ class ChainTest extends TestCase
         $this->assertSame(1234567890, $this->cache->getTimestamp($this->key));
     }
 
-    public function testGetTimestampInB()
+    public function testGetTimestampInB(): void
     {
         $cache = new FilesystemCache($this->directory.'/B');
         $key = $cache->generateKey('_test_', $this->className);
@@ -183,7 +183,7 @@ class ChainTest extends TestCase
         $this->assertSame(1234567890, $this->cache->getTimestamp($this->key));
     }
 
-    public function testGetTimestampInBoth()
+    public function testGetTimestampInBoth(): void
     {
         $cacheA = new FilesystemCache($this->directory.'/A');
         $keyA = $cacheA->generateKey('_test_', $this->className);
@@ -208,7 +208,7 @@ class ChainTest extends TestCase
         $this->assertSame(1234567890, $this->cache->getTimestamp($this->key));
     }
 
-    public function testGetTimestampMissingFile()
+    public function testGetTimestampMissingFile(): void
     {
         $this->assertSame(0, $this->cache->getTimestamp($this->key));
     }
@@ -217,7 +217,7 @@ class ChainTest extends TestCase
      * @dataProvider provideInput
      */
     #[DataProvider('provideInput')]
-    public function testGenerateKey($expected, $input)
+    public function testGenerateKey($expected, $input): void
     {
         $cache = new ChainCache([]);
         $this->assertSame($expected, $cache->generateKey($input, static::class));
diff --git a/tests/Cache/FilesystemTest.php b/tests/Cache/FilesystemTest.php
index 486868d2d..a71e54e4a 100644
--- a/tests/Cache/FilesystemTest.php
+++ b/tests/Cache/FilesystemTest.php
@@ -46,7 +46,7 @@ class FilesystemTest extends TestCase
         }
     }
 
-    public function testLoad()
+    public function testLoad(): void
     {
         $key = $this->directory.'/cache/cachefile.php';
 
@@ -63,7 +63,7 @@ class FilesystemTest extends TestCase
         $this->assertTrue(class_exists($this->className, false));
     }
 
-    public function testLoadMissing()
+    public function testLoadMissing(): void
     {
         $key = $this->directory.'/cache/cachefile.php';
 
@@ -74,7 +74,7 @@ class FilesystemTest extends TestCase
         $this->assertFalse(class_exists($this->className, false));
     }
 
-    public function testWrite()
+    public function testWrite(): void
     {
         $key = $this->directory.'/cache/cachefile.php';
         $content = $this->generateSource();
@@ -89,7 +89,7 @@ class FilesystemTest extends TestCase
         $this->assertSame(file_get_contents($key), $content);
     }
 
-    public function testWriteFailMkdir()
+    public function testWriteFailMkdir(): void
     {
         if (\defined('PHP_WINDOWS_VERSION_BUILD')) {
             $this->markTestSkipped('Read-only directories not possible on Windows.');
@@ -110,7 +110,7 @@ class FilesystemTest extends TestCase
         $this->cache->write($key, $content);
     }
 
-    public function testWriteFailDirWritable()
+    public function testWriteFailDirWritable(): void
     {
         if (\defined('PHP_WINDOWS_VERSION_BUILD')) {
             $this->markTestSkipped('Read-only directories not possible on Windows.');
@@ -133,7 +133,7 @@ class FilesystemTest extends TestCase
         $this->cache->write($key, $content);
     }
 
-    public function testWriteFailWriteFile()
+    public function testWriteFailWriteFile(): void
     {
         $key = $this->directory.'/cache/cachefile.php';
         $content = $this->generateSource();
@@ -150,7 +150,7 @@ class FilesystemTest extends TestCase
         $this->cache->write($key, $content);
     }
 
-    public function testGetTimestamp()
+    public function testGetTimestamp(): void
     {
         $key = $this->directory.'/cache/cachefile.php';
 
@@ -164,7 +164,7 @@ class FilesystemTest extends TestCase
         $this->assertSame(1234567890, $this->cache->getTimestamp($key));
     }
 
-    public function testGetTimestampMissingFile()
+    public function testGetTimestampMissingFile(): void
     {
         $key = $this->directory.'/cache/cachefile.php';
         $this->assertSame(0, $this->cache->getTimestamp($key));
@@ -176,7 +176,7 @@ class FilesystemTest extends TestCase
      * @dataProvider provideDirectories
      */
     #[DataProvider('provideDirectories')]
-    public function testGenerateKey($expected, $input)
+    public function testGenerateKey($expected, $input): void
     {
         $cache = new FilesystemCache($input);
         $this->assertMatchesRegularExpression($expected, $cache->generateKey('_test_', static::class));
diff --git a/tests/Cache/ReadOnlyFilesystemTest.php b/tests/Cache/ReadOnlyFilesystemTest.php
index 78145c95d..c06ad2c4d 100644
--- a/tests/Cache/ReadOnlyFilesystemTest.php
+++ b/tests/Cache/ReadOnlyFilesystemTest.php
@@ -46,7 +46,7 @@ class ReadOnlyFilesystemTest extends TestCase
         }
     }
 
-    public function testLoad()
+    public function testLoad(): void
     {
         $key = $this->directory.'/cache/ro-cachefile.php';
 
@@ -63,7 +63,7 @@ class ReadOnlyFilesystemTest extends TestCase
         $this->assertTrue(class_exists($this->className, false));
     }
 
-    public function testLoadMissing()
+    public function testLoadMissing(): void
     {
         $key = $this->directory.'/cache/cachefile.php';
 
@@ -74,7 +74,7 @@ class ReadOnlyFilesystemTest extends TestCase
         $this->assertFalse(class_exists($this->className, false));
     }
 
-    public function testWrite()
+    public function testWrite(): void
     {
         $key = $this->directory.'/cache/cachefile.php';
         $content = $this->generateSource();
@@ -88,7 +88,7 @@ class ReadOnlyFilesystemTest extends TestCase
         $this->assertFileDoesNotExist($key);
     }
 
-    public function testGetTimestamp()
+    public function testGetTimestamp(): void
     {
         $key = $this->directory.'/cache/cachefile.php';
 
@@ -102,7 +102,7 @@ class ReadOnlyFilesystemTest extends TestCase
         $this->assertSame(1234567890, $this->cache->getTimestamp($key));
     }
 
-    public function testGetTimestampMissingFile()
+    public function testGetTimestampMissingFile(): void
     {
         $key = $this->directory.'/cache/cachefile.php';
         $this->assertSame(0, $this->cache->getTimestamp($key));
@@ -114,7 +114,7 @@ class ReadOnlyFilesystemTest extends TestCase
      * @dataProvider provideDirectories
      */
     #[DataProvider('provideDirectories')]
-    public function testGenerateKey($expected, $input)
+    public function testGenerateKey($expected, $input): void
     {
         $cache = new ReadOnlyFilesystemCache($input);
         $this->assertMatchesRegularExpression($expected, $cache->generateKey('_test_', static::class));
diff --git a/tests/CompilerTest.php b/tests/CompilerTest.php
index 0416b6260..d3d192552 100644
--- a/tests/CompilerTest.php
+++ b/tests/CompilerTest.php
@@ -27,7 +27,7 @@ use Twig\Loader\ArrayLoader;
 
 class CompilerTest extends TestCase
 {
-    public function testStringEncodesSingleQuotesAsHexEscape()
+    public function testStringEncodesSingleQuotesAsHexEscape(): void
     {
         $compiler = new Compiler(new Environment(new ArrayLoader()));
 
@@ -45,7 +45,7 @@ class CompilerTest extends TestCase
         $this->assertSame("it's \"a\" test", $decoded);
     }
 
-    public function testReprNumericValueWithLocale()
+    public function testReprNumericValueWithLocale(): void
     {
         $compiler = new Compiler(new Environment(new ArrayLoader()));
 
diff --git a/tests/ContainerRuntimeLoaderTest.php b/tests/ContainerRuntimeLoaderTest.php
index ae1429257..e3b2a65d7 100644
--- a/tests/ContainerRuntimeLoaderTest.php
+++ b/tests/ContainerRuntimeLoaderTest.php
@@ -26,7 +26,7 @@ use Twig\RuntimeLoader\ContainerRuntimeLoader;
 
 class ContainerRuntimeLoaderTest extends TestCase
 {
-    public function testLoad()
+    public function testLoad(): void
     {
         $container = $this->createMock(ContainerInterface::class);
         $container->expects($this->once())->method('has')->with('stdClass')->willReturn(true);
@@ -37,7 +37,7 @@ class ContainerRuntimeLoaderTest extends TestCase
         $this->assertInstanceOf('stdClass', $loader->load('stdClass'));
     }
 
-    public function testLoadUnknownRuntimeReturnsNull()
+    public function testLoadUnknownRuntimeReturnsNull(): void
     {
         $container = $this->createMock(ContainerInterface::class);
         $container->expects($this->once())->method('has')->with('Foo');
diff --git a/tests/CustomExtensionTest.php b/tests/CustomExtensionTest.php
index 3d3712c71..49136649a 100644
--- a/tests/CustomExtensionTest.php
+++ b/tests/CustomExtensionTest.php
@@ -35,7 +35,7 @@ class CustomExtensionTest extends TestCase
      * @dataProvider provideInvalidExtensions
      */
     #[DataProvider('provideInvalidExtensions'), Group('legacy')]
-    public function testGetInvalidOperators(ExtensionInterface $extension, $expectedExceptionMessage)
+    public function testGetInvalidOperators(ExtensionInterface $extension, $expectedExceptionMessage): void
     {
         $env = new Environment(new ArrayLoader());
         $env->addExtension($extension);
diff --git a/tests/DeprecatedCallableInfoTest.php b/tests/DeprecatedCallableInfoTest.php
index 148717c13..17e3d9427 100644
--- a/tests/DeprecatedCallableInfoTest.php
+++ b/tests/DeprecatedCallableInfoTest.php
@@ -30,7 +30,7 @@ class DeprecatedCallableInfoTest extends TestCase
      * @dataProvider provideTestsForTriggerDeprecation
      */
     #[DataProvider('provideTestsForTriggerDeprecation')]
-    public function testTriggerDeprecation($expected, DeprecatedCallableInfo $info)
+    public function testTriggerDeprecation($expected, DeprecatedCallableInfo $info): void
     {
         $info->setType('function');
         $info->setName('foo');
@@ -61,7 +61,7 @@ class DeprecatedCallableInfoTest extends TestCase
         yield ['Since foo/bar 1.1: Twig Function "foo" is deprecated; use "alt_foo" instead in foo.twig at line 1.', new DeprecatedCallableInfo('foo/bar', '1.1', 'alt_foo')];
     }
 
-    public function testTriggerDeprecationWithoutFileOrLine()
+    public function testTriggerDeprecationWithoutFileOrLine(): void
     {
         $info = new DeprecatedCallableInfo('foo/bar', '1.1');
         $info->setType('function');
diff --git a/tests/EnvironmentTest.php b/tests/EnvironmentTest.php
index 639147dfa..a4b0bf771 100644
--- a/tests/EnvironmentTest.php
+++ b/tests/EnvironmentTest.php
@@ -53,7 +53,7 @@ class EnvironmentTest extends TestCase
 {
     use ExpectDeprecationTrait;
 
-    public function testVersionConstants()
+    public function testVersionConstants(): void
     {
         $version = Environment::VERSION;
         $exploded = explode('-', $version);
@@ -68,7 +68,7 @@ class EnvironmentTest extends TestCase
         $this->assertEquals(Environment::VERSION_ID, Environment::MAJOR_VERSION * 10000 + Environment::MINOR_VERSION * 100 + Environment::RELEASE_VERSION);
     }
 
-    public function testAutoescapeOption()
+    public function testAutoescapeOption(): void
     {
         $loader = new ArrayLoader([
             'html' => '{{ foo }} {{ foo }}',
@@ -90,7 +90,7 @@ class EnvironmentTest extends TestCase
         return $name;
     }
 
-    public function testGlobals()
+    public function testGlobals(): void
     {
         $loader = $this->createMock(LoaderInterface::class);
         $loader->expects($this->any())->method('getSourceContext')->willReturn(new Source('', ''));
@@ -186,7 +186,7 @@ class EnvironmentTest extends TestCase
         }
     }
 
-    public function testExtensionsAreNotInitializedWhenRenderingACompiledTemplate()
+    public function testExtensionsAreNotInitializedWhenRenderingACompiledTemplate(): void
     {
         $cache = new FilesystemCache($dir = sys_get_temp_dir().'/twig');
         $options = ['cache' => $cache, 'auto_reload' => false, 'debug' => false];
@@ -221,7 +221,7 @@ class EnvironmentTest extends TestCase
         FilesystemHelper::removeDir($dir);
     }
 
-    public function testAutoReloadCacheMiss()
+    public function testAutoReloadCacheMiss(): void
     {
         $templateName = __FUNCTION__;
         $templateContent = __FUNCTION__;
@@ -248,7 +248,7 @@ class EnvironmentTest extends TestCase
         $twig->load($templateName);
     }
 
-    public function testAutoReloadCacheHit()
+    public function testAutoReloadCacheHit(): void
     {
         $templateName = __FUNCTION__;
         $templateContent = __FUNCTION__;
@@ -276,7 +276,7 @@ class EnvironmentTest extends TestCase
         $twig->load($templateName);
     }
 
-    public function testAutoReloadOutdatedCacheHit()
+    public function testAutoReloadOutdatedCacheHit(): void
     {
         $templateName = __FUNCTION__;
         $templateContent = __FUNCTION__;
@@ -304,7 +304,7 @@ class EnvironmentTest extends TestCase
         $twig->load($templateName);
     }
 
-    public function testHasGetExtensionByClassName()
+    public function testHasGetExtensionByClassName(): void
     {
         $twig = new Environment(new ArrayLoader());
         $twig->addExtension($ext = new EnvironmentTest_Extension());
@@ -312,7 +312,7 @@ class EnvironmentTest extends TestCase
         $this->assertSame($ext, $twig->getExtension(EnvironmentTest_Extension::class));
     }
 
-    public function testAddExtension()
+    public function testAddExtension(): void
     {
         $twig = new Environment(new ArrayLoader());
         $twig->addExtension(new EnvironmentTest_Extension());
@@ -334,7 +334,7 @@ class EnvironmentTest extends TestCase
         $this->assertTrue($found);
     }
 
-    public function testAddMockExtension()
+    public function testAddMockExtension(): void
     {
         $extension = $this->createMock(ExtensionInterface::class);
         $loader = new ArrayLoader(['page' => 'hey']);
@@ -346,7 +346,7 @@ class EnvironmentTest extends TestCase
         $this->assertTrue($twig->isTemplateFresh('page', time()));
     }
 
-    public function testOverrideExtension()
+    public function testOverrideExtension(): void
     {
         $twig = new Environment(new ArrayLoader());
         $twig->addExtension(new EnvironmentTest_Extension());
@@ -357,7 +357,7 @@ class EnvironmentTest extends TestCase
         $twig->addExtension(new EnvironmentTest_Extension());
     }
 
-    public function testAddRuntimeLoader()
+    public function testAddRuntimeLoader(): void
     {
         $runtimeLoader = $this->createMock(RuntimeLoaderInterface::class);
         $runtimeLoader->expects($this->any())->method('load')->willReturn(new EnvironmentTest_Runtime());
@@ -383,7 +383,7 @@ class EnvironmentTest extends TestCase
         $this->assertEquals('foo', $twig->render('func_string_named_args'));
     }
 
-    public function testFailLoadTemplate()
+    public function testFailLoadTemplate(): void
     {
         $template = 'testFailLoadTemplate.twig';
         $twig = new Environment(new ArrayLoader([$template => false]));
@@ -394,7 +394,7 @@ class EnvironmentTest extends TestCase
         $twig->loadTemplate($twig->getTemplateClass($template), $template, 112233);
     }
 
-    public function testUndefinedFunctionCallback()
+    public function testUndefinedFunctionCallback(): void
     {
         $twig = new Environment(new ArrayLoader());
         $twig->registerUndefinedFunctionCallback(static function (string $name) {
@@ -410,7 +410,7 @@ class EnvironmentTest extends TestCase
         $this->assertSame('dynamic', $function->getName());
     }
 
-    public function testUndefinedFilterCallback()
+    public function testUndefinedFilterCallback(): void
     {
         $twig = new Environment(new ArrayLoader());
         $twig->registerUndefinedFilterCallback(static function (string $name) {
@@ -426,7 +426,7 @@ class EnvironmentTest extends TestCase
         $this->assertSame('dynamic', $filter->getName());
     }
 
-    public function testUndefinedTestCallback()
+    public function testUndefinedTestCallback(): void
     {
         $twig = new Environment(new ArrayLoader());
         $twig->registerUndefinedTestCallback(static function (string $name) {
@@ -442,7 +442,7 @@ class EnvironmentTest extends TestCase
         $this->assertSame('dynamic', $test->getName());
     }
 
-    public function testUndefinedTokenParserCallback()
+    public function testUndefinedTokenParserCallback(): void
     {
         $twig = new Environment(new ArrayLoader());
         $twig->registerUndefinedTokenParserCallback(function (string $name) {
@@ -465,7 +465,7 @@ class EnvironmentTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testLegacyEchoingNode()
+    public function testLegacyEchoingNode(): void
     {
         $loader = new ArrayLoader(['echo_bar' => 'A{% set v %}B{% test %}C{% endset %}D{% test %}E{{ v }}F{% set w %}{% test %}{% endset %}G{{ w }}H']);
 
@@ -501,7 +501,7 @@ EOF
         return $loader;
     }
 
-    public function testResettingGlobals()
+    public function testResettingGlobals(): void
     {
         $twig = new Environment(new ArrayLoader(['index' => '']));
         $twig->addExtension(new class extends AbstractExtension implements GlobalsInterface {
@@ -528,7 +528,7 @@ EOF
         $this->assertNotSame($g3['global_ext'], $g2['global_ext']);
     }
 
-    public function testHotCache()
+    public function testHotCache(): void
     {
         $dir = sys_get_temp_dir().'/twig-hot-cache-test';
         if (is_dir($dir)) {
@@ -693,7 +693,7 @@ class EnvironmentTest_Runtime
 
 class EnvironmentTest_LegacyEchoingNode extends Node
 {
-    public function compile($compiler)
+    public function compile($compiler): void
     {
         $compiler
             ->addDebugInfo($this)
diff --git a/tests/ErrorTest.php b/tests/ErrorTest.php
index c9adeaea0..5ec565a7f 100644
--- a/tests/ErrorTest.php
+++ b/tests/ErrorTest.php
@@ -39,7 +39,7 @@ use Twig\TokenParser\AbstractTokenParser;
 
 class ErrorTest extends TestCase
 {
-    public function testErrorWithObjectFilename()
+    public function testErrorWithObjectFilename(): void
     {
         $error = new Error('foo');
         $error->setSourceContext(new Source('', new \SplFileInfo(__FILE__)));
@@ -47,7 +47,7 @@ class ErrorTest extends TestCase
         $this->assertStringContainsString('tests'.\DIRECTORY_SEPARATOR.'ErrorTest.php', $error->getMessage());
     }
 
-    public function testTwigExceptionGuessWithMissingVarAndArrayLoader()
+    public function testTwigExceptionGuessWithMissingVarAndArrayLoader(): void
     {
         $loader = new ArrayLoader([
             'base.html' => '{% block content %}{% endblock %}',
@@ -76,7 +76,7 @@ EOHTML,
         }
     }
 
-    public function testTwigExceptionGuessWithExceptionAndArrayLoader()
+    public function testTwigExceptionGuessWithExceptionAndArrayLoader(): void
     {
         $loader = new ArrayLoader([
             'base.html' => '{% block content %}{% endblock %}',
@@ -104,7 +104,7 @@ EOHTML,
         }
     }
 
-    public function testTwigExceptionGuessWithMissingVarAndFilesystemLoader()
+    public function testTwigExceptionGuessWithMissingVarAndFilesystemLoader(): void
     {
         $loader = new FilesystemLoader(__DIR__.'/Fixtures/errors');
         $twig = new Environment($loader, ['strict_variables' => true, 'debug' => true, 'cache' => false]);
@@ -123,7 +123,7 @@ EOHTML,
         }
     }
 
-    public function testTwigExceptionGuessWithExceptionAndFilesystemLoader()
+    public function testTwigExceptionGuessWithExceptionAndFilesystemLoader(): void
     {
         $loader = new FilesystemLoader(__DIR__.'/Fixtures/errors');
         $twig = new Environment($loader, ['strict_variables' => true, 'debug' => true, 'cache' => false]);
@@ -146,7 +146,7 @@ EOHTML,
      * @dataProvider getErroredTemplates
      */
     #[DataProvider('getErroredTemplates')]
-    public function testTwigExceptionAddsFileAndLine($templates, $name, $line)
+    public function testTwigExceptionAddsFileAndLine($templates, $name, $line): void
     {
         $loader = new ArrayLoader($templates);
         $twig = new Environment($loader, ['strict_variables' => true, 'debug' => true, 'cache' => false]);
@@ -174,7 +174,7 @@ EOHTML,
         }
     }
 
-    public function testTwigArrayFilterThrowsRuntimeExceptions()
+    public function testTwigArrayFilterThrowsRuntimeExceptions(): void
     {
         $loader = new ArrayLoader([
             'filter-null.html' => <<<EOHTML
@@ -201,7 +201,7 @@ EOHTML,
         }
     }
 
-    public function testTwigArrayMapThrowsRuntimeExceptions()
+    public function testTwigArrayMapThrowsRuntimeExceptions(): void
     {
         $loader = new ArrayLoader([
             'map-null.html' => <<<EOHTML
@@ -228,7 +228,7 @@ EOHTML,
         }
     }
 
-    public function testTwigArrayReduceThrowsRuntimeExceptions()
+    public function testTwigArrayReduceThrowsRuntimeExceptions(): void
     {
         $loader = new ArrayLoader([
             'reduce-null.html' => <<<EOHTML
@@ -253,7 +253,7 @@ EOHTML,
         }
     }
 
-    public function testTwigExceptionUpdateFileAndLineTogether()
+    public function testTwigExceptionUpdateFileAndLineTogether(): void
     {
         $twig = new Environment(new ArrayLoader([
             'index' => "\n\n\n\n{{ foo() }}",
@@ -275,7 +275,7 @@ EOHTML,
      * @dataProvider getErrorWithoutLineAndContextData
      */
     #[DataProvider('getErrorWithoutLineAndContextData')]
-    public function testErrorWithoutLineAndContext(LoaderInterface $loader, bool $debug, bool $addDebugInfo, bool $exceptionWithLineAndContext, int $errorLine)
+    public function testErrorWithoutLineAndContext(LoaderInterface $loader, bool $debug, bool $addDebugInfo, bool $exceptionWithLineAndContext, int $errorLine): void
     {
         $twig = new Environment($loader, ['debug' => $debug, 'cache' => false]);
         $twig->removeCache('no_line_and_context_exception.twig');
@@ -455,7 +455,7 @@ EOHTML,
         ];
     }
 
-    public function testErrorFromArrayLoader()
+    public function testErrorFromArrayLoader(): void
     {
         $templates = [
             'index.twig' => '{% include "include.twig" %}',
@@ -478,7 +478,7 @@ EOHTML,
         }
     }
 
-    public function testErrorFromFilesystemLoader()
+    public function testErrorFromFilesystemLoader(): void
     {
         $twig = new Environment(new FilesystemLoader([$dir = __DIR__.'/Fixtures/errors/extends']), ['debug' => true, 'cache' => false]);
         $include = file_get_contents($dir.'/include.twig');
@@ -496,7 +496,7 @@ EOHTML,
 
 class ErrorTest_Foo
 {
-    public function bar()
+    public function bar(): void
     {
         throw new \Exception('Runtime error...');
     }
diff --git a/tests/ExpressionParserTest.php b/tests/ExpressionParserTest.php
index b48f8d613..4ce9a5d1e 100644
--- a/tests/ExpressionParserTest.php
+++ b/tests/ExpressionParserTest.php
@@ -59,7 +59,7 @@ class ExpressionParserTest extends TestCase
      * @dataProvider getFailingTestsForAssignment
      */
     #[DataProvider('getFailingTestsForAssignment')]
-    public function testCanOnlyAssignToNames($template)
+    public function testCanOnlyAssignToNames($template): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $parser = new Parser($env);
@@ -90,7 +90,7 @@ class ExpressionParserTest extends TestCase
      * @dataProvider getTestsForSequence
      */
     #[DataProvider('getTestsForSequence')]
-    public function testSequenceExpression($template, $expected)
+    public function testSequenceExpression($template, $expected): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $stream = $env->tokenize($source = new Source($template, ''));
@@ -104,7 +104,7 @@ class ExpressionParserTest extends TestCase
      * @dataProvider getFailingTestsForSequence
      */
     #[DataProvider('getFailingTestsForSequence')]
-    public function testSequenceSyntaxError($template)
+    public function testSequenceSyntaxError($template): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $parser = new Parser($env);
@@ -230,7 +230,7 @@ class ExpressionParserTest extends TestCase
         ];
     }
 
-    public function testStringExpressionDoesNotConcatenateTwoConsecutiveStrings()
+    public function testStringExpressionDoesNotConcatenateTwoConsecutiveStrings(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false, 'optimizations' => 0]);
         $stream = $env->tokenize(new Source('{{ "a" "b" }}', 'index'));
@@ -240,7 +240,7 @@ class ExpressionParserTest extends TestCase
         $parser->parse($stream);
     }
 
-    public function testSequenceCompilationError()
+    public function testSequenceCompilationError(): void
     {
         $env = new Environment(new ArrayLoader(['index' => '{{ [1,,2] }}']), ['cache' => false, 'autoescape' => false]);
 
@@ -253,7 +253,7 @@ class ExpressionParserTest extends TestCase
      * @dataProvider getTestsForString
      */
     #[DataProvider('getTestsForString')]
-    public function testStringExpression($template, $expected)
+    public function testStringExpression($template, $expected): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false, 'optimizations' => 0]);
         $stream = $env->tokenize($source = new Source($template, ''));
@@ -311,7 +311,7 @@ class ExpressionParserTest extends TestCase
      * @dataProvider getTestsForNullSafeOperator
      */
     #[DataProvider('getTestsForNullSafeOperator')]
-    public function testNullSafeOperator($template, $data, $expected)
+    public function testNullSafeOperator($template, $data, $expected): void
     {
         $env = new Environment(new ArrayLoader(['template' => $template]), ['strict_variables' => true]);
 
@@ -384,7 +384,7 @@ class ExpressionParserTest extends TestCase
      * @dataProvider getTestForInvalidNullSafeOperatorShortCircuiting
      */
     #[DataProvider('getTestForInvalidNullSafeOperatorShortCircuiting')]
-    public function testInvalidNullSafeOperatorShortCircuiting(string $template, array $data, string $expectedMessage)
+    public function testInvalidNullSafeOperatorShortCircuiting(string $template, array $data, string $expectedMessage): void
     {
         $env = new Environment(new ArrayLoader(['template' => $template]), ['strict_variables' => true]);
 
@@ -408,7 +408,7 @@ class ExpressionParserTest extends TestCase
         ];
     }
 
-    public function testMacroDefinitionDoesNotSupportNonNameVariableName()
+    public function testMacroDefinitionDoesNotSupportNonNameVariableName(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $parser = new Parser($env);
@@ -423,7 +423,7 @@ class ExpressionParserTest extends TestCase
      * @dataProvider             getMacroDefinitionDoesNotSupportNonConstantDefaultValues
      */
     #[DataProvider('getMacroDefinitionDoesNotSupportNonConstantDefaultValues')]
-    public function testMacroDefinitionDoesNotSupportNonConstantDefaultValues($template)
+    public function testMacroDefinitionDoesNotSupportNonConstantDefaultValues($template): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $parser = new Parser($env);
@@ -446,7 +446,7 @@ class ExpressionParserTest extends TestCase
      * @dataProvider getMacroDefinitionSupportsConstantDefaultValues
      */
     #[DataProvider('getMacroDefinitionSupportsConstantDefaultValues')]
-    public function testMacroDefinitionSupportsConstantDefaultValues($template)
+    public function testMacroDefinitionSupportsConstantDefaultValues($template): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $parser = new Parser($env);
@@ -471,7 +471,7 @@ class ExpressionParserTest extends TestCase
         ];
     }
 
-    public function testUnknownFunction()
+    public function testUnknownFunction(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $parser = new Parser($env);
@@ -482,7 +482,7 @@ class ExpressionParserTest extends TestCase
         $parser->parse($env->tokenize(new Source('{{ cycl() }}', 'index')));
     }
 
-    public function testUnknownFunctionWithoutSuggestions()
+    public function testUnknownFunctionWithoutSuggestions(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $parser = new Parser($env);
@@ -493,7 +493,7 @@ class ExpressionParserTest extends TestCase
         $parser->parse($env->tokenize(new Source('{{ foobar() }}', 'index')));
     }
 
-    public function testUnknownFilter()
+    public function testUnknownFilter(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $parser = new Parser($env);
@@ -504,7 +504,7 @@ class ExpressionParserTest extends TestCase
         $parser->parse($env->tokenize(new Source('{{ 1|lowe }}', 'index')));
     }
 
-    public function testUnknownFilterWithoutSuggestions()
+    public function testUnknownFilterWithoutSuggestions(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $parser = new Parser($env);
@@ -515,7 +515,7 @@ class ExpressionParserTest extends TestCase
         $parser->parse($env->tokenize(new Source('{{ 1|foobar }}', 'index')));
     }
 
-    public function testUnknownTest()
+    public function testUnknownTest(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $parser = new Parser($env);
@@ -527,7 +527,7 @@ class ExpressionParserTest extends TestCase
         $parser->parse($stream);
     }
 
-    public function testUnknownTestWithoutSuggestions()
+    public function testUnknownTestWithoutSuggestions(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $parser = new Parser($env);
@@ -538,7 +538,7 @@ class ExpressionParserTest extends TestCase
         $parser->parse($env->tokenize(new Source('{{ 1 is foobar }}', 'index')));
     }
 
-    public function testCompiledCodeForDynamicTest()
+    public function testCompiledCodeForDynamicTest(): void
     {
         $env = new Environment(new ArrayLoader(['index' => '{{ "a" is foo_foo_bar_bar }}']), ['cache' => false, 'autoescape' => false]);
         $env->addExtension(new class extends AbstractExtension {
@@ -553,7 +553,7 @@ class ExpressionParserTest extends TestCase
         $this->assertStringContainsString('$this->env->getTest(\'*_foo_*_bar\')->getCallable()("foo", "bar", "a")', $env->compile($env->parse($env->tokenize(new Source($env->getLoader()->getSourceContext('index')->getCode(), 'index')))));
     }
 
-    public function testCompiledCodeForDynamicFunction()
+    public function testCompiledCodeForDynamicFunction(): void
     {
         $env = new Environment(new ArrayLoader(['index' => '{{ foo_foo_bar_bar("a") }}']), ['cache' => false, 'autoescape' => false]);
         $env->addExtension(new class extends AbstractExtension {
@@ -568,7 +568,7 @@ class ExpressionParserTest extends TestCase
         $this->assertStringContainsString('$this->env->getFunction(\'*_foo_*_bar\')->getCallable()("foo", "bar", "a")', $env->compile($env->parse($env->tokenize(new Source($env->getLoader()->getSourceContext('index')->getCode(), 'index')))));
     }
 
-    public function testCompiledCodeForDynamicFilter()
+    public function testCompiledCodeForDynamicFilter(): void
     {
         $env = new Environment(new ArrayLoader(['index' => '{{ "a"|foo_foo_bar_bar }}']), ['cache' => false, 'autoescape' => false]);
         $env->addExtension(new class extends AbstractExtension {
@@ -583,7 +583,7 @@ class ExpressionParserTest extends TestCase
         $this->assertStringContainsString('$this->env->getFilter(\'*_foo_*_bar\')->getCallable()("foo", "bar", "a")', $env->compile($env->parse($env->tokenize(new Source($env->getLoader()->getSourceContext('index')->getCode(), 'index')))));
     }
 
-    public function testNotReadyFunctionWithNoConstructor()
+    public function testNotReadyFunctionWithNoConstructor(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $env->addFunction(new TwigFunction('foo', 'foo', ['node_class' => NotReadyFunctionExpressionWithNoConstructor::class]));
@@ -593,7 +593,7 @@ class ExpressionParserTest extends TestCase
         $this->expectNotToPerformAssertions();
     }
 
-    public function testNotReadyFilterWithNoConstructor()
+    public function testNotReadyFilterWithNoConstructor(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $env->addFilter(new TwigFilter('foo', 'foo', ['node_class' => NotReadyFilterExpressionWithNoConstructor::class]));
@@ -603,7 +603,7 @@ class ExpressionParserTest extends TestCase
         $this->expectNotToPerformAssertions();
     }
 
-    public function testNotReadyTestWithNoConstructor()
+    public function testNotReadyTestWithNoConstructor(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $env->addTest(new TwigTest('foo', 'foo', ['node_class' => NotReadyTestExpressionWithNoConstructor::class]));
@@ -617,7 +617,7 @@ class ExpressionParserTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testNotReadyFunction()
+    public function testNotReadyFunction(): void
     {
         $this->expectDeprecation('Since twig/twig 3.12: Twig node "Twig\Tests\NotReadyFunctionExpression" is not marked as ready for passing a "TwigFunction" in the constructor instead of its name; please update your code and then add #[FirstClassTwigCallableReady] attribute to the constructor.');
         $this->expectDeprecation('Since twig/twig 3.12: Not passing an instance of "TwigFunction" when creating a "foo" function of type "Twig\Tests\NotReadyFunctionExpression" is deprecated.');
@@ -633,7 +633,7 @@ class ExpressionParserTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testNotReadyFilter()
+    public function testNotReadyFilter(): void
     {
         $this->expectDeprecation('Since twig/twig 3.12: Twig node "Twig\Tests\NotReadyFilterExpression" is not marked as ready for passing a "TwigFilter" in the constructor instead of its name; please update your code and then add #[FirstClassTwigCallableReady] attribute to the constructor.');
         $this->expectDeprecation('Since twig/twig 3.12: Not passing an instance of "TwigFilter" when creating a "foo" filter of type "Twig\Tests\NotReadyFilterExpression" is deprecated.');
@@ -649,7 +649,7 @@ class ExpressionParserTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testNotReadyTest()
+    public function testNotReadyTest(): void
     {
         $this->expectDeprecation('Since twig/twig 3.12: Twig node "Twig\Tests\NotReadyTestExpression" is not marked as ready for passing a "TwigTest" in the constructor instead of its name; please update your code and then add #[FirstClassTwigCallableReady] attribute to the constructor.');
         $this->expectDeprecation('Since twig/twig 3.12: Not passing an instance of "TwigTest" when creating a "foo" test of type "Twig\Tests\NotReadyTestExpression" is deprecated.');
@@ -661,7 +661,7 @@ class ExpressionParserTest extends TestCase
         $parser->parse($env->tokenize(new Source('{{ 1 is foo }}', 'index')));
     }
 
-    public function testReadyFunction()
+    public function testReadyFunction(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $env->addFunction(new TwigFunction('foo', 'foo', ['node_class' => ReadyFunctionExpression::class]));
@@ -671,7 +671,7 @@ class ExpressionParserTest extends TestCase
         $this->expectNotToPerformAssertions();
     }
 
-    public function testReadyFilter()
+    public function testReadyFilter(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $env->addFilter(new TwigFilter('foo', 'foo', ['node_class' => ReadyFilterExpression::class]));
@@ -681,7 +681,7 @@ class ExpressionParserTest extends TestCase
         $this->expectNotToPerformAssertions();
     }
 
-    public function testReadyTest()
+    public function testReadyTest(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $env->addTest(new TwigTest('foo', 'foo', ['node_class' => ReadyTestExpression::class]));
@@ -691,7 +691,7 @@ class ExpressionParserTest extends TestCase
         $this->expectNotToPerformAssertions();
     }
 
-    public function testTwoWordTestPrecedence()
+    public function testTwoWordTestPrecedence(): void
     {
         // a "empty element" test must have precedence over "empty"
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
@@ -702,7 +702,7 @@ class ExpressionParserTest extends TestCase
         $this->expectNotToPerformAssertions();
     }
 
-    public function testUnaryPrecedenceChange()
+    public function testUnaryPrecedenceChange(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
         $env->addExtension(new class extends AbstractExtension {
@@ -730,7 +730,7 @@ class ExpressionParserTest extends TestCase
      * @dataProvider getBindingPowerTests
      */
     #[DataProvider('getBindingPowerTests')]
-    public function testBindingPower(string $expression, string $expectedExpression, mixed $expectedResult, array $context = [])
+    public function testBindingPower(string $expression, string $expectedExpression, mixed $expectedResult, array $context = []): void
     {
         $env = new Environment(new ArrayLoader([
             'expression' => $expression,
@@ -814,7 +814,7 @@ class ExpressionParserTest extends TestCase
         yield '= stronger than ternary' => ['{% do c = 4 ? 0 : -1 %}{{ c }}', '{% do c = (4 ? 0 : -1) %}{{ c }}', eval('return 4 ? 0 : -1;')];
     }
 
-    public function testLiteralExpressionParserGetOperatorTokensReturnsEmptyArray()
+    public function testLiteralExpressionParserGetOperatorTokensReturnsEmptyArray(): void
     {
         $env = new Environment(new ArrayLoader());
         $parser = $env->getExpressionParsers()->getByClass(LiteralExpressionParser::class);
@@ -823,7 +823,7 @@ class ExpressionParserTest extends TestCase
         $this->assertSame('literal', $parser->getName());
     }
 
-    public function testExpressionParserGetOperatorTokensDefaultBehavior()
+    public function testExpressionParserGetOperatorTokensDefaultBehavior(): void
     {
         $env = new Environment(new ArrayLoader());
 
@@ -836,7 +836,7 @@ class ExpressionParserTest extends TestCase
         }
     }
 
-    public function testLiteralIsNotRegisteredAsOperator()
+    public function testLiteralIsNotRegisteredAsOperator(): void
     {
         // Ensure "literal" is not in the operator registry
         $env = new Environment(new ArrayLoader());
diff --git a/tests/Extension/AttributeExtensionTest.php b/tests/Extension/AttributeExtensionTest.php
index c5d9ddd39..b7b3decd0 100644
--- a/tests/Extension/AttributeExtensionTest.php
+++ b/tests/Extension/AttributeExtensionTest.php
@@ -30,7 +30,7 @@ class AttributeExtensionTest extends TestCase
      * @dataProvider provideFilters
      */
     #[DataProvider('provideFilters')]
-    public function testFilter(string $name, string $method, array $options)
+    public function testFilter(string $name, string $method, array $options): void
     {
         $extension = new AttributeExtension(ExtensionWithAttributes::class);
         foreach ($extension->getFilters() as $filter) {
@@ -62,7 +62,7 @@ class AttributeExtensionTest extends TestCase
      * @dataProvider provideFunctions
      */
     #[DataProvider('provideFunctions')]
-    public function testFunction(string $name, string $method, array $options)
+    public function testFunction(string $name, string $method, array $options): void
     {
         $extension = new AttributeExtension(ExtensionWithAttributes::class);
         foreach ($extension->getFunctions() as $function) {
@@ -94,7 +94,7 @@ class AttributeExtensionTest extends TestCase
      * @dataProvider provideTests
      */
     #[DataProvider('provideTests')]
-    public function testTest(string $name, string $method, array $options)
+    public function testTest(string $name, string $method, array $options): void
     {
         $extension = new AttributeExtension(ExtensionWithAttributes::class);
         foreach ($extension->getTests() as $test) {
@@ -121,7 +121,7 @@ class AttributeExtensionTest extends TestCase
         yield 'deprecated positional' => ['deprecated_positional_test', 'deprecatedPositionalTest', ['deprecation_info' => new DeprecatedCallableInfo('foo/bar', '1.2')]];
     }
 
-    public function testFilterRequireOneArgument()
+    public function testFilterRequireOneArgument(): void
     {
         $extension = new AttributeExtension(FilterWithoutValue::class);
 
@@ -131,7 +131,7 @@ class AttributeExtensionTest extends TestCase
         $extension->getTests();
     }
 
-    public function testTestRequireOneArgument()
+    public function testTestRequireOneArgument(): void
     {
         $extension = new AttributeExtension(TestWithoutValue::class);
 
@@ -141,14 +141,14 @@ class AttributeExtensionTest extends TestCase
         $extension->getTests();
     }
 
-    public function testLastModifiedWithObject()
+    public function testLastModifiedWithObject(): void
     {
         $extension = new AttributeExtension(\stdClass::class);
 
         $this->assertSame(filemtime((new \ReflectionClass(AttributeExtension::class))->getFileName()), $extension->getLastModified());
     }
 
-    public function testLastModifiedWithClass()
+    public function testLastModifiedWithClass(): void
     {
         $extension = new AttributeExtension('__CLASS_FOR_TEST_LAST_MODIFIED__');
 
@@ -163,7 +163,7 @@ class AttributeExtensionTest extends TestCase
         }
     }
 
-    public function testMultipleRegistrations()
+    public function testMultipleRegistrations(): void
     {
         $extensionSet = new ExtensionSet();
         $extensionSet->addExtension($extension1 = new AttributeExtension(ExtensionWithAttributes::class));
diff --git a/tests/Extension/CoreTest.php b/tests/Extension/CoreTest.php
index faada348a..57fc0ef92 100644
--- a/tests/Extension/CoreTest.php
+++ b/tests/Extension/CoreTest.php
@@ -41,7 +41,7 @@ class CoreTest extends TestCase
      * @dataProvider provideCycleCases
      */
     #[DataProvider('provideCycleCases')]
-    public function testCycleFunction($values, $position, $expected)
+    public function testCycleFunction($values, $position, $expected): void
     {
         $this->assertSame($expected, CoreExtension::cycle($values, $position));
     }
@@ -65,7 +65,7 @@ class CoreTest extends TestCase
      * @dataProvider provideCycleInvalidCases
      */
     #[DataProvider('provideCycleInvalidCases')]
-    public function testCycleFunctionThrowRuntimeError($values, mixed $position = null)
+    public function testCycleFunctionThrowRuntimeError($values, mixed $position = null): void
     {
         $this->expectException(RuntimeError::class);
         CoreExtension::cycle($values, $position ?? 0);
@@ -84,7 +84,7 @@ class CoreTest extends TestCase
      * @dataProvider getRandomFunctionTestData
      */
     #[DataProvider('getRandomFunctionTestData')]
-    public function testRandomFunction(array $expectedInArray, $value1, $value2 = null)
+    public function testRandomFunction(array $expectedInArray, $value1, $value2 = null): void
     {
         for ($i = 0; $i < 100; ++$i) {
             $this->assertTrue(\in_array(CoreExtension::random('UTF-8', $value1, $value2), $expectedInArray, true)); // assertContains() would not consider the type
@@ -140,7 +140,7 @@ class CoreTest extends TestCase
         ];
     }
 
-    public function testRandomFunctionWithoutParameter()
+    public function testRandomFunctionWithoutParameter(): void
     {
         $max = mt_getrandmax();
 
@@ -150,7 +150,7 @@ class CoreTest extends TestCase
         }
     }
 
-    public function testRandomFunctionReturnsAsIs()
+    public function testRandomFunctionReturnsAsIs(): void
     {
         $this->assertSame('', CoreExtension::random('UTF-8', ''));
 
@@ -158,13 +158,13 @@ class CoreTest extends TestCase
         $this->assertSame($instance, CoreExtension::random('UTF-8', $instance));
     }
 
-    public function testRandomFunctionOfEmptyArrayThrowsException()
+    public function testRandomFunctionOfEmptyArrayThrowsException(): void
     {
         $this->expectException(RuntimeError::class);
         CoreExtension::random('UTF-8', []);
     }
 
-    public function testRandomFunctionOnNonUTF8String()
+    public function testRandomFunctionOnNonUTF8String(): void
     {
         $text = iconv('UTF-8', 'ISO-8859-1', 'Äé');
         for ($i = 0; $i < 30; ++$i) {
@@ -173,7 +173,7 @@ class CoreTest extends TestCase
         }
     }
 
-    public function testReverseFilterOnNonUTF8String()
+    public function testReverseFilterOnNonUTF8String(): void
     {
         $input = iconv('UTF-8', 'ISO-8859-1', 'Äé');
         $output = iconv('ISO-8859-1', 'UTF-8', CoreExtension::reverse('ISO-8859-1', $input));
@@ -185,7 +185,7 @@ class CoreTest extends TestCase
      * @dataProvider provideTwigFirstCases
      */
     #[DataProvider('provideTwigFirstCases')]
-    public function testTwigFirst($expected, $input)
+    public function testTwigFirst($expected, $input): void
     {
         $this->assertSame($expected, CoreExtension::first('UTF-8', $input));
     }
@@ -207,7 +207,7 @@ class CoreTest extends TestCase
      * @dataProvider provideTwigLastCases
      */
     #[DataProvider('provideTwigLastCases')]
-    public function testTwigLast($expected, $input)
+    public function testTwigLast($expected, $input): void
     {
         $this->assertSame($expected, CoreExtension::last('UTF-8', $input));
     }
@@ -229,7 +229,7 @@ class CoreTest extends TestCase
      * @dataProvider provideArrayKeyCases
      */
     #[DataProvider('provideArrayKeyCases')]
-    public function testArrayKeysFilter(array $expected, $input)
+    public function testArrayKeysFilter(array $expected, $input): void
     {
         $this->assertSame($expected, CoreExtension::keys($input));
     }
@@ -253,7 +253,7 @@ class CoreTest extends TestCase
      * @dataProvider provideInFilterCases
      */
     #[DataProvider('provideInFilterCases')]
-    public function testInFilter($expected, $value, $compare)
+    public function testInFilter($expected, $value, $compare): void
     {
         $this->assertSame($expected, CoreExtension::inFilter($value, $compare));
     }
@@ -282,7 +282,7 @@ class CoreTest extends TestCase
      * @dataProvider provideSliceFilterCases
      */
     #[DataProvider('provideSliceFilterCases')]
-    public function testSliceFilter($expected, $input, $start, $length = null, $preserveKeys = false)
+    public function testSliceFilter($expected, $input, $start, $length = null, $preserveKeys = false): void
     {
         $this->assertSame($expected, CoreExtension::slice('UTF-8', $input, $start, $length, $preserveKeys));
     }
@@ -312,13 +312,13 @@ class CoreTest extends TestCase
      * @dataProvider provideCompareCases
      */
     #[DataProvider('provideCompareCases')]
-    public function testCompare($expected, $a, $b)
+    public function testCompare($expected, $a, $b): void
     {
         $this->assertSame($expected, CoreExtension::compare($a, $b));
         $this->assertSame($expected, -CoreExtension::compare($b, $a));
     }
 
-    public function testCompareNAN()
+    public function testCompareNAN(): void
     {
         $this->assertSame(1, CoreExtension::compare(\NAN, 'NAN'));
         $this->assertSame(1, CoreExtension::compare('NAN', \NAN));
@@ -384,7 +384,7 @@ class CoreTest extends TestCase
         ];
     }
 
-    public function testSandboxedInclude()
+    public function testSandboxedInclude(): void
     {
         $twig = new Environment(new ArrayLoader([
             'index' => '{{ include("included", sandboxed: true) }}',
@@ -399,7 +399,7 @@ class CoreTest extends TestCase
         $twig->render('index');
     }
 
-    public function testSandboxedIncludeWithPreloadedTemplate()
+    public function testSandboxedIncludeWithPreloadedTemplate(): void
     {
         $twig = new Environment(new ArrayLoader([
             'index' => '{{ include("included", sandboxed: true) }}',
@@ -418,7 +418,7 @@ class CoreTest extends TestCase
         $twig->render('index');
     }
 
-    public function testSandboxedIncludeResultStaysEscapedWhenAssigned()
+    public function testSandboxedIncludeResultStaysEscapedWhenAssigned(): void
     {
         $twig = new Environment(new ArrayLoader([
             'index' => "{% set body = include('included', sandboxed: true) %}[{{ body }}]",
@@ -429,7 +429,7 @@ class CoreTest extends TestCase
         $this->assertSame('[&lt;script&gt;]', $twig->render('index', ['evil' => '<script>']));
     }
 
-    public function testIncludeReturnsMarkupForRenderedContent()
+    public function testIncludeReturnsMarkupForRenderedContent(): void
     {
         $twig = new Environment(new ArrayLoader(['included' => 'content']));
 
@@ -439,21 +439,21 @@ class CoreTest extends TestCase
         $this->assertSame('content', (string) $result);
     }
 
-    public function testIncludeReturnsAnEmptyStringForEmptyContent()
+    public function testIncludeReturnsAnEmptyStringForEmptyContent(): void
     {
         $twig = new Environment(new ArrayLoader(['included' => '']));
 
         $this->assertSame('', CoreExtension::include($twig, [], 'included'));
     }
 
-    public function testIncludeReturnsAnEmptyStringForIgnoredMissingTemplate()
+    public function testIncludeReturnsAnEmptyStringForIgnoredMissingTemplate(): void
     {
         $twig = new Environment(new ArrayLoader([]));
 
         $this->assertSame('', CoreExtension::include($twig, [], 'missing', ignoreMissing: true));
     }
 
-    public function testLastModified()
+    public function testLastModified(): void
     {
         $this->assertGreaterThan(1000000000, (new CoreExtension())->getLastModified());
     }
@@ -462,7 +462,7 @@ class CoreTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testCycleWithArrayAccessAndTraversableButNotCountable()
+    public function testCycleWithArrayAccessAndTraversableButNotCountable(): void
     {
         $this->expectDeprecation('Since twig/twig 3.12: Passing a non-countable sequence of values to "Twig\Extension\CoreExtension::cycle()" is deprecated.');
 
diff --git a/tests/Extension/EscaperTest.php b/tests/Extension/EscaperTest.php
index 71d816040..a1f5ec02e 100644
--- a/tests/Extension/EscaperTest.php
+++ b/tests/Extension/EscaperTest.php
@@ -37,7 +37,7 @@ class EscaperTest extends TestCase
      * @group legacy
      */
     #[DataProvider('provideCustomEscaperCases'), Group('legacy')]
-    public function testCustomEscaper($expected, $string, $strategy)
+    public function testCustomEscaper($expected, $string, $strategy): void
     {
         $twig = new Environment(new ArrayLoader());
         $escaperExt = $twig->getExtension(EscaperExtension::class);
@@ -60,7 +60,7 @@ class EscaperTest extends TestCase
      * @group legacy
      */
     #[DataProvider('provideCustomEscaperCases'), Group('legacy')]
-    public function testCustomEscaperWithoutCallingSetEscaperRuntime($expected, $string, $strategy)
+    public function testCustomEscaperWithoutCallingSetEscaperRuntime($expected, $string, $strategy): void
     {
         $twig = new Environment(new ArrayLoader());
         $escaperExt = $twig->getExtension(EscaperExtension::class);
@@ -72,7 +72,7 @@ class EscaperTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testCustomEscapersOnMultipleEnvs()
+    public function testCustomEscapersOnMultipleEnvs(): void
     {
         $env1 = new Environment(new ArrayLoader());
         $escaperExt1 = $env1->getExtension(EscaperExtension::class);
@@ -90,7 +90,7 @@ class EscaperTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSafeClassesUseCustomRuntimeLoader()
+    public function testSafeClassesUseCustomRuntimeLoader(): void
     {
         $runtime = new EscaperRuntime();
         $twig = new Environment(new ArrayLoader());
@@ -105,7 +105,7 @@ class EscaperTest extends TestCase
         $this->assertArrayHasKey('ThisClassIsSafe', $runtime->safeClasses);
     }
 
-    public function testLastModified()
+    public function testLastModified(): void
     {
         $this->assertGreaterThan(1000000000, (new EscaperExtension())->getLastModified());
     }
diff --git a/tests/Extension/Fixtures/ExtensionWithAttributes.php b/tests/Extension/Fixtures/ExtensionWithAttributes.php
index 64b1088fb..8678a5459 100644
--- a/tests/Extension/Fixtures/ExtensionWithAttributes.php
+++ b/tests/Extension/Fixtures/ExtensionWithAttributes.php
@@ -20,147 +20,147 @@ use Twig\Environment;
 class ExtensionWithAttributes
 {
     #[AsTwigFilter(name: 'foo', isSafe: ['html'])]
-    public function fooFilter(string|int $string)
+    public function fooFilter(string|int $string): void
     {
     }
 
     #[AsTwigFilter('with_context_filter', needsContext: true)]
-    public function withContextFilter(array $context, string $string)
+    public function withContextFilter(array $context, string $string): void
     {
     }
 
     #[AsTwigFilter('with_env_filter')]
-    public function withEnvFilter(Environment $env, string $string)
+    public function withEnvFilter(Environment $env, string $string): void
     {
     }
 
     #[AsTwigFilter('with_env_and_context_filter', needsContext: true)]
-    public function withEnvAndContextFilter(Environment $env, array $context, array $data)
+    public function withEnvAndContextFilter(Environment $env, array $context, array $data): void
     {
     }
 
     #[AsTwigFilter('with_sandbox_filter', needsIsSandboxed: true)]
-    public function withSandboxFilter(bool $isSandboxed, string $string)
+    public function withSandboxFilter(bool $isSandboxed, string $string): void
     {
     }
 
     #[AsTwigFilter('always_allowed_filter', alwaysAllowedInSandbox: true)]
-    public function alwaysAllowedFilter(string $string)
+    public function alwaysAllowedFilter(string $string): void
     {
     }
 
     #[AsTwigFilter('variadic_filter')]
-    public function variadicFilter(string ...$strings)
+    public function variadicFilter(string ...$strings): void
     {
     }
 
     #[AsTwigFilter('deprecated_filter', deprecationInfo: new DeprecatedCallableInfo('foo/bar', '1.2'))]
-    public function deprecatedFilter(string $string)
+    public function deprecatedFilter(string $string): void
     {
     }
 
     #[AsTwigFilter('deprecated_positional_filter', null, null, null, null, null, null, null, null, new DeprecatedCallableInfo('foo/bar', '1.2'))]
-    public function deprecatedPositionalFilter(string $string)
+    public function deprecatedPositionalFilter(string $string): void
     {
     }
 
     #[AsTwigFilter('pattern_*_filter')]
-    public function patternFilter(string $string)
+    public function patternFilter(string $string): void
     {
     }
 
     #[AsTwigFunction(name: 'foo', isSafe: ['html'])]
-    public function fooFunction(string|int $string)
+    public function fooFunction(string|int $string): void
     {
     }
 
     #[AsTwigFunction('with_context_function', needsContext: true)]
-    public function withContextFunction(array $context, string $string)
+    public function withContextFunction(array $context, string $string): void
     {
     }
 
     #[AsTwigFunction('with_env_function')]
-    public function withEnvFunction(Environment $env, string $string)
+    public function withEnvFunction(Environment $env, string $string): void
     {
     }
 
     #[AsTwigFunction('with_env_and_context_function', needsContext: true)]
-    public function withEnvAndContextFunction(Environment $env, array $context, string $string)
+    public function withEnvAndContextFunction(Environment $env, array $context, string $string): void
     {
     }
 
     #[AsTwigFunction('with_sandbox_function', needsIsSandboxed: true)]
-    public function withSandboxFunction(bool $isSandboxed, string $string)
+    public function withSandboxFunction(bool $isSandboxed, string $string): void
     {
     }
 
     #[AsTwigFunction('always_allowed_function', alwaysAllowedInSandbox: true)]
-    public function alwaysAllowedFunction(string $string)
+    public function alwaysAllowedFunction(string $string): void
     {
     }
 
     #[AsTwigFunction('no_arg_function')]
-    public function noArgFunction()
+    public function noArgFunction(): void
     {
     }
 
     #[AsTwigFunction('variadic_function')]
-    public function variadicFunction(string ...$strings)
+    public function variadicFunction(string ...$strings): void
     {
     }
 
     #[AsTwigFunction('deprecated_function', deprecationInfo: new DeprecatedCallableInfo('foo/bar', '1.2'))]
-    public function deprecatedFunction(string $string)
+    public function deprecatedFunction(string $string): void
     {
     }
 
     #[AsTwigFunction('deprecated_positional_function', null, null, null, null, null, null, new DeprecatedCallableInfo('foo/bar', '1.2'))]
-    public function deprecatedPositionalFunction(string $string)
+    public function deprecatedPositionalFunction(string $string): void
     {
     }
 
     #[AsTwigTest(name: 'foo')]
-    public function fooTest(string|int $value)
+    public function fooTest(string|int $value): void
     {
     }
 
     #[AsTwigTest('variadic_test')]
-    public function variadicTest(string ...$value)
+    public function variadicTest(string ...$value): void
     {
     }
 
     #[AsTwigTest('with_context_test', needsContext: true)]
-    public function withContextTest(array $context, $argument)
+    public function withContextTest(array $context, $argument): void
     {
     }
 
     #[AsTwigTest('with_env_test')]
-    public function withEnvTest(Environment $env, $argument)
+    public function withEnvTest(Environment $env, $argument): void
     {
     }
 
     #[AsTwigTest('with_env_and_context_test', needsContext: true)]
-    public function withEnvAndContextTest(Environment $env, array $context, $argument)
+    public function withEnvAndContextTest(Environment $env, array $context, $argument): void
     {
     }
 
     #[AsTwigTest('with_sandbox_test', needsIsSandboxed: true)]
-    public function withSandboxTest(bool $isSandboxed, $argument)
+    public function withSandboxTest(bool $isSandboxed, $argument): void
     {
     }
 
     #[AsTwigTest('always_allowed_test', alwaysAllowedInSandbox: true)]
-    public function alwaysAllowedTest($value)
+    public function alwaysAllowedTest($value): void
     {
     }
 
     #[AsTwigTest('deprecated_test', deprecationInfo: new DeprecatedCallableInfo('foo/bar', '1.2'))]
-    public function deprecatedTest($value, $argument)
+    public function deprecatedTest($value, $argument): void
     {
     }
 
     #[AsTwigTest('deprecated_positional_test', null, null, null, null, new DeprecatedCallableInfo('foo/bar', '1.2'))]
-    public function deprecatedPositionalTest($value, $argument)
+    public function deprecatedPositionalTest($value, $argument): void
     {
     }
 }
diff --git a/tests/Extension/Fixtures/FilterWithoutValue.php b/tests/Extension/Fixtures/FilterWithoutValue.php
index 4946fc047..1da1a68fa 100644
--- a/tests/Extension/Fixtures/FilterWithoutValue.php
+++ b/tests/Extension/Fixtures/FilterWithoutValue.php
@@ -16,7 +16,7 @@ use Twig\Attribute\AsTwigFilter;
 class FilterWithoutValue
 {
     #[AsTwigFilter('my_filter')]
-    public function myFilter()
+    public function myFilter(): void
     {
     }
 }
diff --git a/tests/Extension/Fixtures/TestWithoutValue.php b/tests/Extension/Fixtures/TestWithoutValue.php
index fe28d00c2..1c8834635 100644
--- a/tests/Extension/Fixtures/TestWithoutValue.php
+++ b/tests/Extension/Fixtures/TestWithoutValue.php
@@ -16,7 +16,7 @@ use Twig\Attribute\AsTwigTest;
 class TestWithoutValue
 {
     #[AsTwigTest('my_test')]
-    public function myTest()
+    public function myTest(): void
     {
     }
 }
diff --git a/tests/Extension/LegacyDebugFunctionsTest.php b/tests/Extension/LegacyDebugFunctionsTest.php
index 73716834a..6f684efbe 100644
--- a/tests/Extension/LegacyDebugFunctionsTest.php
+++ b/tests/Extension/LegacyDebugFunctionsTest.php
@@ -23,7 +23,7 @@ use Twig\Loader\ArrayLoader;
 #[Group('legacy')]
 class LegacyDebugFunctionsTest extends TestCase
 {
-    public function testDump()
+    public function testDump(): void
     {
         $env = new Environment(new ArrayLoader());
 
diff --git a/tests/Extension/LegacyStringLoaderFunctionsTest.php b/tests/Extension/LegacyStringLoaderFunctionsTest.php
index 8bebf5609..7cac3c664 100644
--- a/tests/Extension/LegacyStringLoaderFunctionsTest.php
+++ b/tests/Extension/LegacyStringLoaderFunctionsTest.php
@@ -23,7 +23,7 @@ use Twig\Loader\ArrayLoader;
 #[Group('legacy')]
 class LegacyStringLoaderFunctionsTest extends TestCase
 {
-    public function testTemplateFromString()
+    public function testTemplateFromString(): void
     {
         $env = new Environment(new ArrayLoader());
 
diff --git a/tests/Extension/SandboxStateChangeTest.php b/tests/Extension/SandboxStateChangeTest.php
index f6b1fcc6e..6df49c895 100644
--- a/tests/Extension/SandboxStateChangeTest.php
+++ b/tests/Extension/SandboxStateChangeTest.php
@@ -38,7 +38,7 @@ class SandboxStateChangeTest extends TestCase
 {
     use ExpectDeprecationTrait;
 
-    public function testEnableSandboxAfterFirstRender()
+    public function testEnableSandboxAfterFirstRender(): void
     {
         [$twig, $sandbox] = $this->build(['t' => '{{ "foo"|upper }}'], new SecurityPolicy(allowedFilters: []), false);
 
@@ -51,7 +51,7 @@ class SandboxStateChangeTest extends TestCase
         $twig->render('t');
     }
 
-    public function testDisableSandboxAfterFirstRender()
+    public function testDisableSandboxAfterFirstRender(): void
     {
         // Use enableSandbox() to toggle a non-global sandbox so disableSandbox() actually has an effect.
         [$twig, $sandbox] = $this->build(['t' => '{{ "foo"|upper }}'], new SecurityPolicy(allowedFilters: []), false);
@@ -69,7 +69,7 @@ class SandboxStateChangeTest extends TestCase
         $this->assertSame('FOO', $twig->render('t'));
     }
 
-    public function testSetSecurityPolicyTightening()
+    public function testSetSecurityPolicyTightening(): void
     {
         $permissive = new SecurityPolicy(allowedFilters: ['upper', 'escape']);
         [$twig, $sandbox] = $this->build(['t' => '{{ "foo"|upper }}'], $permissive, true);
@@ -83,7 +83,7 @@ class SandboxStateChangeTest extends TestCase
         $twig->render('t');
     }
 
-    public function testSetSecurityPolicyLoosening()
+    public function testSetSecurityPolicyLoosening(): void
     {
         $strict = new SecurityPolicy(allowedFilters: []);
         [$twig, $sandbox] = $this->build(['t' => '{{ "foo"|upper }}'], $strict, true);
@@ -104,7 +104,7 @@ class SandboxStateChangeTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSourcePolicyDecisionFlip()
+    public function testSourcePolicyDecisionFlip(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -127,7 +127,7 @@ class SandboxStateChangeTest extends TestCase
         $twig->render('t');
     }
 
-    public function testPreWarmedParentTemplateThroughExtends()
+    public function testPreWarmedParentTemplateThroughExtends(): void
     {
         $templates = [
             'parent.twig' => '{% block c %}default{% endblock %}{{ "hi"|upper }}',
@@ -149,7 +149,7 @@ class SandboxStateChangeTest extends TestCase
         $twig->render('child.twig');
     }
 
-    public function testPreWarmedSharedViaSandboxedInclude()
+    public function testPreWarmedSharedViaSandboxedInclude(): void
     {
         $templates = [
             'top' => '{{ include("user", sandboxed=true) }}',
@@ -174,7 +174,7 @@ class SandboxStateChangeTest extends TestCase
         $twig->render('top');
     }
 
-    public function testMacroFromPreWarmedTemplate()
+    public function testMacroFromPreWarmedTemplate(): void
     {
         $templates = [
             'macros.twig' => '{% macro greet(name) %}{{ name|upper }}{% endmacro %}',
@@ -200,7 +200,7 @@ class SandboxStateChangeTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSandboxTagAroundIncludeOfPreWarmedTemplate()
+    public function testSandboxTagAroundIncludeOfPreWarmedTemplate(): void
     {
         $this->expectDeprecation('Since twig/twig 3.15: The "sandbox" tag is deprecated in "wrapper" at line 1.');
 
@@ -222,7 +222,7 @@ class SandboxStateChangeTest extends TestCase
         $twig->render('wrapper');
     }
 
-    public function testTagBypassThroughPreWarmedParent()
+    public function testTagBypassThroughPreWarmedParent(): void
     {
         $templates = [
             'parent.twig' => '{% block c %}{% for i in 1..2 %}{{ i }}{% endfor %}{% endblock %}',
@@ -244,7 +244,7 @@ class SandboxStateChangeTest extends TestCase
         $twig->render('child.twig');
     }
 
-    public function testFunctionBypassThroughPreWarmedParent()
+    public function testFunctionBypassThroughPreWarmedParent(): void
     {
         $templates = [
             'parent.twig' => '{% block c %}{{ range(1, 2)|first }}{% endblock %}',
@@ -266,7 +266,7 @@ class SandboxStateChangeTest extends TestCase
         $twig->render('child.twig');
     }
 
-    public function testDynamicParentFilterRejectedWhenReachedViaMacroImport()
+    public function testDynamicParentFilterRejectedWhenReachedViaMacroImport(): void
     {
         // Regression: getTemplateForMacro() walks getParent() to find the
         // macro on a parent template. When the imported template has a
@@ -300,7 +300,7 @@ class SandboxStateChangeTest extends TestCase
         $this->assertSame(0, $evilCalls, 'The forbidden filter must not be invoked before the security check runs.');
     }
 
-    public function testDynamicParentFunctionRejectedWhenReachedViaMacroImport()
+    public function testDynamicParentFunctionRejectedWhenReachedViaMacroImport(): void
     {
         // Same root cause as the filter case, but for functions called from
         // within the dynamic parent expression.
@@ -330,7 +330,7 @@ class SandboxStateChangeTest extends TestCase
         $this->assertSame(0, $evilCalls, 'The forbidden function must not be invoked before the security check runs.');
     }
 
-    public function testDynamicParentFilterRejectedOnPreWarmedTemplate()
+    public function testDynamicParentFilterRejectedOnPreWarmedTemplate(): void
     {
         // Same bypass, but reached after the template has been pre-warmed
         // outside the sandbox (which would have otherwise short-circuited
@@ -366,7 +366,7 @@ class SandboxStateChangeTest extends TestCase
         $this->assertSame(1, $evilCalls, 'The forbidden filter must not be invoked after the sandbox is enabled.');
     }
 
-    public function testRepeatedRendersInStableSandboxedStateRunCheckEachTime()
+    public function testRepeatedRendersInStableSandboxedStateRunCheckEachTime(): void
     {
         $counter = new CountingSecurityPolicy(new SecurityPolicy(allowedFilters: ['upper']));
         [$twig] = $this->build(['t' => '{{ "x"|upper }}'], $counter, true);
@@ -380,7 +380,7 @@ class SandboxStateChangeTest extends TestCase
         $this->assertGreaterThanOrEqual(5, $counter->callCount);
     }
 
-    public function testNoCheckWhenSandboxRemainsOff()
+    public function testNoCheckWhenSandboxRemainsOff(): void
     {
         $counter = new CountingSecurityPolicy(new SecurityPolicy());
         [$twig] = $this->build(['t' => '{{ "x"|upper }}'], $counter, false);
diff --git a/tests/Extension/SandboxTest.php b/tests/Extension/SandboxTest.php
index 0a134cb9d..c13f9871c 100644
--- a/tests/Extension/SandboxTest.php
+++ b/tests/Extension/SandboxTest.php
@@ -112,7 +112,7 @@ class SandboxTest extends TestCase
      * @dataProvider getSandboxedForCoreTagsTests
      */
     #[DataProvider('getSandboxedForCoreTagsTests')]
-    public function testSandboxForCoreTags(string $tag, string $template)
+    public function testSandboxForCoreTags(string $tag, string $template): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates, []);
 
@@ -151,7 +151,7 @@ class SandboxTest extends TestCase
      * @group legacy
      */
     #[DataProvider('getSandboxedForExtendsAndUseTagsTests'), Group('legacy')]
-    public function testSandboxForExtendsAndUseTags(string $tag, string $template)
+    public function testSandboxForExtendsAndUseTags(string $tag, string $template): void
     {
         $this->expectDeprecation(\sprintf('Since twig/twig 3.12: The "%s" tag is always allowed in sandboxes, but won\'t be in 4.0, please enable it explicitly in your sandbox policy if needed (or enable strict mode on the security policy to opt-in to the 4.0 behavior now).', $tag));
 
@@ -171,7 +171,7 @@ class SandboxTest extends TestCase
      * @group legacy
      */
     #[DataProvider('getSandboxedForParserCallableFunctionsTests'), Group('legacy')]
-    public function testSandboxForParserCallableFunctions(string $function, string $templateName, array $extraTemplates, array $allowedTags, array $allowedMethods, array $allowedProperties, array $context, string $expected)
+    public function testSandboxForParserCallableFunctions(string $function, string $templateName, array $extraTemplates, array $allowedTags, array $allowedMethods, array $allowedProperties, array $context, string $expected): void
     {
         $this->expectDeprecation(\sprintf('Since twig/twig 3.27: The "%s" function is always allowed in sandboxes, but won\'t be in 4.0, please enable it explicitly in your sandbox policy if needed (or enable strict mode on the security policy to opt-in to the 4.0 behavior now).', $function));
 
@@ -232,7 +232,7 @@ class SandboxTest extends TestCase
      * @dataProvider getAllowedParserCallableFunctionsTests
      */
     #[DataProvider('getAllowedParserCallableFunctionsTests')]
-    public function testSandboxWithAllowedParserCallableFunctions(string $templateName, array $extraTemplates, array $allowedTags, array $allowedMethods, array $allowedProperties, array $allowedFunctions, array $context, string $expected)
+    public function testSandboxWithAllowedParserCallableFunctions(string $templateName, array $extraTemplates, array $allowedTags, array $allowedMethods, array $allowedProperties, array $allowedFunctions, array $context, string $expected): void
     {
         $twig = $this->getEnvironment(true, [], $extraTemplates, $allowedTags, [], $allowedMethods, $allowedProperties, $allowedFunctions);
         $this->assertSame($expected, $twig->load($templateName)->render($context));
@@ -272,7 +272,7 @@ class SandboxTest extends TestCase
      * @dataProvider getStrictSandboxRejectsGrandfatheredTagsTests
      */
     #[DataProvider('getStrictSandboxRejectsGrandfatheredTagsTests')]
-    public function testStrictSandboxRejectsGrandfatheredTags(string $tag, string $template)
+    public function testStrictSandboxRejectsGrandfatheredTags(string $tag, string $template): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates, [], [], [], [], [], null, true);
 
@@ -292,7 +292,7 @@ class SandboxTest extends TestCase
      * @dataProvider getStrictSandboxRejectsGrandfatheredFunctionsTests
      */
     #[DataProvider('getStrictSandboxRejectsGrandfatheredFunctionsTests')]
-    public function testStrictSandboxRejectsGrandfatheredFunctions(string $function, string $templateName, array $extraTemplates, array $allowedTags, array $context)
+    public function testStrictSandboxRejectsGrandfatheredFunctions(string $function, string $templateName, array $extraTemplates, array $allowedTags, array $context): void
     {
         $twig = $this->getEnvironment(true, [], $extraTemplates, $allowedTags, [], [], [], [], null, true);
 
@@ -332,7 +332,7 @@ class SandboxTest extends TestCase
         ];
     }
 
-    public function testStrictSandboxStillAllowsExplicitlyAllowedGrandfatheredNames()
+    public function testStrictSandboxStillAllowsExplicitlyAllowedGrandfatheredNames(): void
     {
         $twig = $this->getEnvironment(
             true,
@@ -353,7 +353,7 @@ class SandboxTest extends TestCase
         $this->assertSame('PARENT CHILD - OK', $twig->load('child')->render(['data' => ['x' => 'OK']]));
     }
 
-    public function testStrictModeCanBeEnabledViaSetterAfterConstruction()
+    public function testStrictModeCanBeEnabledViaSetterAfterConstruction(): void
     {
         $policy = new SecurityPolicy([], [], [], [], []);
         $policy->setStrict(true);
@@ -366,7 +366,7 @@ class SandboxTest extends TestCase
      * @dataProvider getAlwaysAllowedCoreTests
      */
     #[DataProvider('getAlwaysAllowedCoreTests')]
-    public function testSandboxAllowsAlwaysAllowedCoreTests(string $template)
+    public function testSandboxAllowsAlwaysAllowedCoreTests(string $template): void
     {
         // the safe built-in tests are always allowed in a sandbox (they carry
         // the `always_allowed_in_sandbox` flag), so they need neither an
@@ -396,7 +396,7 @@ class SandboxTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSandboxForConstantTest()
+    public function testSandboxForConstantTest(): void
     {
         // unlike the other built-in tests, "constant" reaches into the PHP
         // runtime, so it is not always allowed and is deprecated until 4.0
@@ -410,7 +410,7 @@ class SandboxTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSandboxForUserDefinedTest()
+    public function testSandboxForUserDefinedTest(): void
     {
         $this->expectDeprecation('Since twig/twig 3.28: The "unsafe" test is always allowed in sandboxes, but won\'t be in 4.0, please enable it explicitly in your sandbox policy if needed (or enable strict mode on the security policy to opt-in to the 4.0 behavior now).');
 
@@ -426,7 +426,7 @@ class SandboxTest extends TestCase
         $this->assertSame(1, $called);
     }
 
-    public function testSandboxAllowsAllowListedTest()
+    public function testSandboxAllowsAllowListedTest(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ "x" is unsafe ? "y" }}'], [], [], [], [], [], null, false, ['unsafe']);
         $twig->addTest(new TwigTest('unsafe', static fn ($v): bool => true));
@@ -434,7 +434,7 @@ class SandboxTest extends TestCase
         $this->assertSame('y', $twig->load('index')->render([]));
     }
 
-    public function testStrictSandboxRejectsConstantTest()
+    public function testStrictSandboxRejectsConstantTest(): void
     {
         // "constant" is the only built-in test that is not always allowed
         $twig = $this->getEnvironment(true, [], ['index' => '{{ 1 is constant("PHP_INT_MAX") ? "y" }}'], [], [], [], [], [], null, true);
@@ -445,14 +445,14 @@ class SandboxTest extends TestCase
         $twig->load('index')->render([]);
     }
 
-    public function testStrictSandboxStillAllowsAllowListedTest()
+    public function testStrictSandboxStillAllowsAllowListedTest(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ 1 is constant("PHP_INT_MAX") ? "y" : "n" }}'], [], [], [], [], [], null, true, ['constant']);
 
         $this->assertSame('n', $twig->load('index')->render([]));
     }
 
-    public function testStrictSandboxRejectsUserDefinedTest()
+    public function testStrictSandboxRejectsUserDefinedTest(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ "x" is unsafe ? "y" }}'], [], [], [], [], [], null, true);
         $twig->addTest(new TwigTest('unsafe', static fn ($v): bool => true));
@@ -463,7 +463,7 @@ class SandboxTest extends TestCase
         $twig->load('index')->render([]);
     }
 
-    public function testImplicitBooleanCoercionDoesNotRequireAllowListingTests()
+    public function testImplicitBooleanCoercionDoesNotRequireAllowListingTests(): void
     {
         // `{% if %}`, ternary, `?:`, `??`, and `|default` conditions are coerced
         // to a boolean through `true`/`defined`/`null` tests that the compiler
@@ -475,7 +475,7 @@ class SandboxTest extends TestCase
         $this->assertSame('acdef', $twig->load('index')->render(['x' => true, 'y' => false]));
     }
 
-    public function testStrictSandboxRejectedTestCarriesSourceAndLine()
+    public function testStrictSandboxRejectedTestCarriesSourceAndLine(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => "{{ 1 }}\n{{ 1 is constant('PHP_INT_MAX') ? 'y' }}"], [], [], [], [], [], null, true);
 
@@ -489,7 +489,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testStrictModeRejectsTestsViaSetter()
+    public function testStrictModeRejectsTestsViaSetter(): void
     {
         $policy = new SecurityPolicy([], [], [], [], []);
         $policy->setStrict(true);
@@ -498,7 +498,7 @@ class SandboxTest extends TestCase
         $policy->checkSecurity([], [], [], ['empty']);
     }
 
-    public function testAllowedTestsCanBeUpdatedViaSetter()
+    public function testAllowedTestsCanBeUpdatedViaSetter(): void
     {
         $policy = new SecurityPolicy([], [], [], [], []);
         $policy->setStrict(true);
@@ -515,7 +515,7 @@ class SandboxTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testLegacySecurityPolicyWithoutTestsParameterTriggersDeprecation()
+    public function testLegacySecurityPolicyWithoutTestsParameterTriggersDeprecation(): void
     {
         $this->expectDeprecation('Since twig/twig 3.28: The "Twig\Tests\Extension\LegacySandboxSecurityPolicy::checkSecurity()" method will take a 4th "array $tests" argument in 4.0; not declaring it is deprecated.');
 
@@ -532,7 +532,7 @@ class SandboxTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testLegacyCheckSecurityCallWithSourceAs4thArgumentTriggersDeprecation()
+    public function testLegacyCheckSecurityCallWithSourceAs4thArgumentTriggersDeprecation(): void
     {
         $this->expectDeprecation('Since twig/twig 3.28: Passing a "Twig\Source" as the 4th argument of "Twig\Extension\SandboxExtension::checkSecurity()" is deprecated; pass an array of tests instead.');
 
@@ -545,7 +545,7 @@ class SandboxTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testLegacyCheckSecurityNodeWithoutUsedTestsTriggersDeprecation()
+    public function testLegacyCheckSecurityNodeWithoutUsedTestsTriggersDeprecation(): void
     {
         $this->expectDeprecation('Since twig/twig 3.28: Not passing the "$usedTests" argument to "Twig\Node\CheckSecurityNode::__construct()" is deprecated; it will be required in 4.0.');
 
@@ -556,14 +556,14 @@ class SandboxTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testLegacySecurityPolicyCheckSecurityWithoutTestsArgTriggersDeprecation()
+    public function testLegacySecurityPolicyCheckSecurityWithoutTestsArgTriggersDeprecation(): void
     {
         $this->expectDeprecation('Since twig/twig 3.28: Not passing the "$tests" argument to "Twig\Sandbox\SecurityPolicy::checkSecurity()" is deprecated; it will be required in 4.0.');
 
         (new SecurityPolicy([], [], [], [], []))->checkSecurity([], [], []);
     }
 
-    public function testSandboxWithInheritance()
+    public function testSandboxWithInheritance(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates, ['extends', 'block']);
 
@@ -573,13 +573,13 @@ class SandboxTest extends TestCase
         $twig->load('1_child')->render([]);
     }
 
-    public function testSandboxGloballySet()
+    public function testSandboxGloballySet(): void
     {
         $twig = $this->getEnvironment(false, [], self::$templates);
         $this->assertEquals('FOO', $twig->load('1_basic')->render(self::$params), 'Sandbox does nothing if it is disabled globally');
     }
 
-    public function testSandboxUnallowedPropertyAccessor()
+    public function testSandboxUnallowedPropertyAccessor(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates);
         try {
@@ -591,7 +591,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxUnallowedArrayIndexAccessor()
+    public function testSandboxUnallowedArrayIndexAccessor(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates);
 
@@ -611,7 +611,7 @@ class SandboxTest extends TestCase
      * @dataProvider provideNonStringArrayAccessKeys
      */
     #[DataProvider('provideNonStringArrayAccessKeys')]
-    public function testSandboxNonStringKeyAccessDoesNotTriggerImplicitConversionDeprecation(string $template, string $expectedKey)
+    public function testSandboxNonStringKeyAccessDoesNotTriggerImplicitConversionDeprecation(string $template, string $expectedKey): void
     {
         $loader = new ArrayLoader(['t' => $template]);
         $twig = new Environment($loader);
@@ -670,7 +670,7 @@ class SandboxTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testIfSandBoxIsDisabledAfterSyntaxErrorLegacy()
+    public function testIfSandBoxIsDisabledAfterSyntaxErrorLegacy(): void
     {
         $twig = $this->getEnvironment(false, [], self::$templates);
         try {
@@ -682,7 +682,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testIfSandBoxIsDisabledAfterSyntaxError()
+    public function testIfSandBoxIsDisabledAfterSyntaxError(): void
     {
         $twig = $this->getEnvironment(false, [], self::$templates);
         try {
@@ -694,7 +694,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxGloballyFalseUnallowedFilterWithIncludeTemplateFromStringSandboxed()
+    public function testSandboxGloballyFalseUnallowedFilterWithIncludeTemplateFromStringSandboxed(): void
     {
         $twig = $this->getEnvironment(false, [], self::$templates);
         $twig->addExtension(new StringLoaderExtension());
@@ -706,7 +706,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxGloballyTrueUnallowedFilterWithIncludeTemplateFromStringSandboxed()
+    public function testSandboxGloballyTrueUnallowedFilterWithIncludeTemplateFromStringSandboxed(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates, [], [], [], [], ['include', 'template_from_string']);
         $twig->addExtension(new StringLoaderExtension());
@@ -718,14 +718,14 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxGloballyFalseUnallowedFilterWithIncludeTemplateFromStringNotSandboxed()
+    public function testSandboxGloballyFalseUnallowedFilterWithIncludeTemplateFromStringNotSandboxed(): void
     {
         $twig = $this->getEnvironment(false, [], self::$templates);
         $twig->addExtension(new StringLoaderExtension());
         $this->assertSame('FABIEN', $twig->load('1_basic2_include_template_from_string')->render(self::$params));
     }
 
-    public function testSandboxGloballyTrueUnallowedFilterWithIncludeTemplateFromStringNotSandboxed()
+    public function testSandboxGloballyTrueUnallowedFilterWithIncludeTemplateFromStringNotSandboxed(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates, [], [], [], [], ['include', 'template_from_string']);
         $twig->addExtension(new StringLoaderExtension());
@@ -737,7 +737,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxUnallowedFilter()
+    public function testSandboxUnallowedFilter(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates);
         try {
@@ -748,7 +748,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxUnallowedTag()
+    public function testSandboxUnallowedTag(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates);
         try {
@@ -759,7 +759,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxUnallowedProperty()
+    public function testSandboxUnallowedProperty(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates);
         try {
@@ -775,7 +775,7 @@ class SandboxTest extends TestCase
      * @dataProvider getSandboxUnallowedToStringTests
      */
     #[DataProvider('getSandboxUnallowedToStringTests')]
-    public function testSandboxUnallowedToString($template)
+    public function testSandboxUnallowedToString($template): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => $template], ['if', 'do', 'for', 'set'], ['upper', 'join', 'replace', 'format', 'split'], ['Twig\Tests\Extension\FooObject' => 'getAnotherFooObject'], [], ['random', 'range', 'my_func']);
         $twig->addFunction(new TwigFunction('my_func', static fn ($a) => (string) $a));
@@ -864,7 +864,7 @@ class SandboxTest extends TestCase
         ];
     }
 
-    public function testSandboxBlocksToStringOnFunctionReturn()
+    public function testSandboxBlocksToStringOnFunctionReturn(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ make_obj() }}'], [], [], [], [], ['make_obj']);
         $twig->addFunction(new TwigFunction('make_obj', static fn () => new FooObject()));
@@ -877,7 +877,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxBlocksToStringOnFilterReturn()
+    public function testSandboxBlocksToStringOnFilterReturn(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ "x"|to_obj }}'], [], ['to_obj']);
         $twig->addFilter(new TwigFilter('to_obj', static fn () => new FooObject()));
@@ -890,7 +890,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxBlocksToStringOnDynamicAttributeName()
+    public function testSandboxBlocksToStringOnDynamicAttributeName(): void
     {
         $twig = $this->getEnvironment(true, ['strict_variables' => true], ['index' => '{{ arr[obj] }}'], [], [], ['Twig\Tests\Extension\FooObject' => 'getAnotherFooObject']);
         try {
@@ -902,7 +902,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxBlocksToStringOnDynamicMacroName()
+    public function testSandboxBlocksToStringOnDynamicMacroName(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => <<<EOF
             {% import _self as macros %}
@@ -919,7 +919,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxBlocksToStringOnIncludeTemplateName()
+    public function testSandboxBlocksToStringOnIncludeTemplateName(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{% include obj %}'], ['include']);
         try {
@@ -931,7 +931,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxBlocksToStringOnExtendsTemplateName()
+    public function testSandboxBlocksToStringOnExtendsTemplateName(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{% extends obj %}'], ['extends']);
         try {
@@ -943,7 +943,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxBlocksToStringOnBlockFunctionTemplateName()
+    public function testSandboxBlocksToStringOnBlockFunctionTemplateName(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ block("content", obj) }}'], [], [], [], [], ['block']);
         try {
@@ -955,7 +955,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxBlocksToStringOnEmbedTemplateName()
+    public function testSandboxBlocksToStringOnEmbedTemplateName(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{% embed obj %}{% endembed %}'], ['embed', 'extends']);
         try {
@@ -967,7 +967,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxBlocksToStringOnIsConstantTestArgument()
+    public function testSandboxBlocksToStringOnIsConstantTestArgument(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{% if "x" is constant(obj) %}LEAK{% endif %}'], ['if'], [], [], [], [], null, false, ['constant']);
         try {
@@ -979,7 +979,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxBlocksToStringOnDeprecatedMessage()
+    public function testSandboxBlocksToStringOnDeprecatedMessage(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{% deprecated obj %}'], ['deprecated']);
         $previous = set_error_handler(static fn () => true, \E_USER_DEPRECATED);
@@ -994,7 +994,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxKeepsSelfImportShortcut()
+    public function testSandboxKeepsSelfImportShortcut(): void
     {
         $tpl = "{% macro local_lower(s) %}{{ s|lower }}{% endmacro %}{% from _self import local_lower %}{{ local_lower('A') }}";
         $twig = $this->getEnvironment(true, [], ['index' => $tpl], ['from', 'macro', 'import'], ['lower']);
@@ -1006,7 +1006,7 @@ class SandboxTest extends TestCase
      * @dataProvider getSandboxAllowedToStringTests
      */
     #[DataProvider('getSandboxAllowedToStringTests')]
-    public function testSandboxAllowedToString($template, $output)
+    public function testSandboxAllowedToString($template, $output): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => $template], ['set', 'do'], [], ['Twig\Tests\Extension\FooObject' => ['foo', 'getAnotherFooObject']], [], [], null, false, ['constant']);
         $this->assertEquals($output, $twig->load('index')->render(self::$params));
@@ -1031,7 +1031,7 @@ class SandboxTest extends TestCase
         ];
     }
 
-    public function testSandboxAllowMethodToString()
+    public function testSandboxAllowMethodToString(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates, [], [], ['Twig\Tests\Extension\FooObject' => '__toString']);
         FooObject::reset();
@@ -1039,7 +1039,7 @@ class SandboxTest extends TestCase
         $this->assertEquals(1, FooObject::$called['__toString'], 'Sandbox only calls method once');
     }
 
-    public function testSandboxAllowsArrayDynamicKeyWhenToStringAllowed()
+    public function testSandboxAllowsArrayDynamicKeyWhenToStringAllowed(): void
     {
         $twig = $this->getEnvironment(true, [], [
             'index' => '{% set arr = {(obj): "v", (obj.anotherFooObject): "v2"} %}{{ arr|keys|join(",") }}',
@@ -1048,7 +1048,7 @@ class SandboxTest extends TestCase
         $this->assertSame('foo', $twig->load('index')->render(self::$params));
     }
 
-    public function testSandboxAllowMethodToStringDisabled()
+    public function testSandboxAllowMethodToStringDisabled(): void
     {
         $twig = $this->getEnvironment(false, [], self::$templates);
         FooObject::reset();
@@ -1056,7 +1056,7 @@ class SandboxTest extends TestCase
         $this->assertEquals(1, FooObject::$called['__toString'], 'Sandbox only calls method once');
     }
 
-    public function testSandboxUnallowedFunction()
+    public function testSandboxUnallowedFunction(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates);
         try {
@@ -1067,7 +1067,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxUnallowedRangeOperator()
+    public function testSandboxUnallowedRangeOperator(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates);
         try {
@@ -1078,7 +1078,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxAllowMethodFoo()
+    public function testSandboxAllowMethodFoo(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates, [], [], ['Twig\Tests\Extension\FooObject' => 'foo']);
         FooObject::reset();
@@ -1086,25 +1086,25 @@ class SandboxTest extends TestCase
         $this->assertEquals(1, FooObject::$called['foo'], 'Sandbox only calls method once');
     }
 
-    public function testSandboxAllowFilter()
+    public function testSandboxAllowFilter(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates, [], ['upper']);
         $this->assertEquals('FABIEN', $twig->load('1_basic2')->render(self::$params), 'Sandbox allow some filters');
     }
 
-    public function testSandboxAllowTag()
+    public function testSandboxAllowTag(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates, ['if']);
         $this->assertEquals('foo', $twig->load('1_basic3')->render(self::$params), 'Sandbox allow some tags');
     }
 
-    public function testSandboxAllowProperty()
+    public function testSandboxAllowProperty(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates, [], [], [], ['Twig\Tests\Extension\FooObject' => 'bar']);
         $this->assertEquals('bar', $twig->load('1_basic4')->render(self::$params), 'Sandbox allow some properties');
     }
 
-    public function testSandboxAllowDestructuring()
+    public function testSandboxAllowDestructuring(): void
     {
         $template = '{% do {bar: x, foo: y} = obj %}{{ x }}-{{ y }}';
         $twig = $this->getEnvironment(true, [], ['index' => $template], ['do'], [], ['Twig\Tests\Extension\FooObject' => 'foo'], ['Twig\Tests\Extension\FooObject' => 'bar']);
@@ -1112,7 +1112,7 @@ class SandboxTest extends TestCase
         $this->assertSame('bar-foo', $twig->load('index')->render(self::$params), 'Sandbox allows destructuring when properties and methods are allowed');
     }
 
-    public function testSandboxUnallowedDestructuringProperty()
+    public function testSandboxUnallowedDestructuringProperty(): void
     {
         $template = '{% do {bar: x} = obj %}{{ x }}';
         $twig = $this->getEnvironment(true, [], ['index' => $template], ['do']);
@@ -1125,7 +1125,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxUnallowedDestructuringMethod()
+    public function testSandboxUnallowedDestructuringMethod(): void
     {
         $template = '{% do {foo: y} = obj %}{{ y }}';
         $twig = $this->getEnvironment(true, [], ['index' => $template], ['do'], [], [], ['Twig\Tests\Extension\FooObject' => 'foo']);
@@ -1138,19 +1138,19 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxAllowFunction()
+    public function testSandboxAllowFunction(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates, [], [], [], [], ['cycle']);
         $this->assertEquals('bar', $twig->load('1_basic7')->render(self::$params), 'Sandbox allow some functions');
     }
 
-    public function testSandboxAllowRangeOperator()
+    public function testSandboxAllowRangeOperator(): void
     {
         $twig = $this->getEnvironment(true, [], self::$templates, [], [], [], [], ['range']);
         $this->assertEquals('1', $twig->load('1_range_operator')->render(self::$params), 'Sandbox allow the range operator');
     }
 
-    public function testSandboxAllowMethodsCaseInsensitive()
+    public function testSandboxAllowMethodsCaseInsensitive(): void
     {
         foreach (['getfoobar', 'getFoobar', 'getFooBar'] as $name) {
             $twig = $this->getEnvironment(true, [], self::$templates, [], [], ['Twig\Tests\Extension\FooObject' => $name]);
@@ -1162,7 +1162,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testSandboxLocallySetForAnInclude()
+    public function testSandboxLocallySetForAnInclude(): void
     {
         self::$templates = [
             '2_basic' => '{{ obj.foo }}{% include "2_included" %}{{ obj.foo }}',
@@ -1186,7 +1186,7 @@ class SandboxTest extends TestCase
         }
     }
 
-    public function testMacrosInASandbox()
+    public function testMacrosInASandbox(): void
     {
         $twig = $this->getEnvironment(true, ['autoescape' => 'html'], ['index' => <<<EOF
 {%- import _self as macros %}
@@ -1200,7 +1200,7 @@ EOF
         $this->assertEquals('<p>username</p>', $twig->load('index')->render([]));
     }
 
-    public function testSelfMacroReferenceWithStringLiteralDoesNotInjectPhp()
+    public function testSelfMacroReferenceWithStringLiteralDoesNotInjectPhp(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ _self.(\'foo + 1; trigger_error("BAD-MACRO-REF") //\') }}']);
 
@@ -1228,7 +1228,7 @@ EOF
         $this->assertFalse($triggered, 'No PHP from the template literal must execute.');
     }
 
-    public function testImportedTemplateMacroReferenceWithBadIdentifierDoesNotInjectPhp()
+    public function testImportedTemplateMacroReferenceWithBadIdentifierDoesNotInjectPhp(): void
     {
         $payload = '{% import "m" as m %}{{ m.(\'foo + 1; trigger_error("BAD-IMPORT-REF") //\') }}';
         $twig = $this->getEnvironment(true, [], [
@@ -1258,7 +1258,7 @@ EOF
         $this->assertFalse($triggered, 'No PHP from the template literal must execute.');
     }
 
-    public function testSelfMacroReferenceWithValidIdentifierStillWorks()
+    public function testSelfMacroReferenceWithValidIdentifierStillWorks(): void
     {
         $twig = $this->getEnvironment(true, ['autoescape' => 'html'], ['index' => <<<EOF
             {%- macro greet(n) %}Hi {{ n }}{% endmacro %}
@@ -1269,7 +1269,7 @@ EOF
         $this->assertSame('Hi World', $twig->load('index')->render([]));
     }
 
-    public function testSandboxDisabledAfterIncludeFunctionError()
+    public function testSandboxDisabledAfterIncludeFunctionError(): void
     {
         $twig = $this->getEnvironment(false, [], self::$templates);
 
@@ -1289,7 +1289,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSandboxTagIncludeWithPreloadedTemplate()
+    public function testSandboxTagIncludeWithPreloadedTemplate(): void
     {
         $twig = $this->getEnvironment(false, [], [
             'index' => '{% sandbox %}{% include "included" %}{% endsandbox %}',
@@ -1307,7 +1307,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSandboxTagIncludeIgnoreMissingWithPreloadedTemplate()
+    public function testSandboxTagIncludeIgnoreMissingWithPreloadedTemplate(): void
     {
         $twig = $this->getEnvironment(false, [], [
             'index' => '{% sandbox %}{% include "included" ignore missing %}{% endsandbox %}',
@@ -1321,7 +1321,7 @@ EOF
         $twig->load('index')->render([]);
     }
 
-    public function testSandboxWithNoClosureFilter()
+    public function testSandboxWithNoClosureFilter(): void
     {
         $twig = $this->getEnvironment(true, ['autoescape' => 'html'], ['index' => <<<EOF
 {{ ["foo", "bar", ""]|filter("trim")|join(", ") }}
@@ -1334,7 +1334,7 @@ EOF
         $twig->load('index')->render([]);
     }
 
-    public function testSandboxWithClosureFilter()
+    public function testSandboxWithClosureFilter(): void
     {
         $twig = $this->getEnvironment(true, ['autoescape' => 'html'], ['index' => <<<EOF
 {{ ["foo", "bar", ""]|filter(v => v != "")|join(", ") }}
@@ -1344,7 +1344,7 @@ EOF
         $this->assertSame('foo, bar', $twig->load('index')->render([]));
     }
 
-    public function testMultipleClassMatchesViaInheritanceInAllowedMethods()
+    public function testMultipleClassMatchesViaInheritanceInAllowedMethods(): void
     {
         $twig_child_first = $this->getEnvironment(true, [], self::$templates, [], [], [
             'Twig\Tests\Extension\ChildClass' => ['ChildMethod'],
@@ -1382,7 +1382,7 @@ EOF
         $this->expectNotToPerformAssertions();
     }
 
-    public function testSandboxAllowsColumnFilterOnAllowedProperty()
+    public function testSandboxAllowsColumnFilterOnAllowedProperty(): void
     {
         $params = ['obj' => new ColumnObject()];
         $twig = $this->getEnvironment(true, [], ['index' => "{{ [obj]|column('bar')|first }}"], [], ['column', 'first'], [], ['Twig\Tests\Extension\ColumnObject' => ['bar']]);
@@ -1390,7 +1390,7 @@ EOF
         $this->assertSame('bar', $twig->load('index')->render($params));
     }
 
-    public function testSandboxBlocksColumnFilterOnDisallowedProperty()
+    public function testSandboxBlocksColumnFilterOnDisallowedProperty(): void
     {
         $params = ['obj' => new ColumnObject()];
         $twig = $this->getEnvironment(true, [], ['index' => "{{ [obj]|column('bar')|first }}"], [], ['column', 'first']);
@@ -1404,7 +1404,7 @@ EOF
         }
     }
 
-    public function testSandboxBlocksColumnFilterOnDisallowedIndex()
+    public function testSandboxBlocksColumnFilterOnDisallowedIndex(): void
     {
         $params = ['obj' => new ColumnObject()];
         $twig = $this->getEnvironment(true, [], ['index' => "{{ [obj]|column('bar', 'foo')|keys|first }}"], [], ['column', 'first', 'keys'], [], ['Twig\Tests\Extension\ColumnObject' => ['bar']]);
@@ -1418,7 +1418,7 @@ EOF
         }
     }
 
-    public function testSandboxBlocksColumnFilterOnMagicGetter()
+    public function testSandboxBlocksColumnFilterOnMagicGetter(): void
     {
         $params = ['magic' => new MagicObject()];
         $twig = $this->getEnvironment(true, [], ['index' => "{{ [magic]|column('anything')|first }}"], [], ['column', 'first']);
@@ -1436,7 +1436,7 @@ EOF
      * @dataProvider getStringableTraversableBypassTemplates
      */
     #[DataProvider('getStringableTraversableBypassTemplates')]
-    public function testSandboxBlocksToStringInStringableTraversable(string $template)
+    public function testSandboxBlocksToStringInStringableTraversable(string $template): void
     {
         $twig = $this->getEnvironment(
             true,
@@ -1468,7 +1468,7 @@ EOF
      * @dataProvider getStringableTraversableBypassTemplates
      */
     #[DataProvider('getStringableTraversableBypassTemplates'), Group('legacy')]
-    public function testSourcePolicySandboxBlocksToStringInStringableTraversable(string $template)
+    public function testSourcePolicySandboxBlocksToStringInStringableTraversable(string $template): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -1500,7 +1500,7 @@ EOF
         }
     }
 
-    public function testSandboxAllowsPrintingStringableTraversableWhenToStringAllowed()
+    public function testSandboxAllowsPrintingStringableTraversableWhenToStringAllowed(): void
     {
         // Printing the container itself yields its `__toString()` value. The
         // sandbox materialises the iterable to also policy-check the elements
@@ -1524,7 +1524,7 @@ EOF
      * @dataProvider getCyclicTraversableTemplates
      */
     #[DataProvider('getCyclicTraversableTemplates')]
-    public function testSandboxHandlesCyclicTraversableWithoutStackOverflow(string $template)
+    public function testSandboxHandlesCyclicTraversableWithoutStackOverflow(string $template): void
     {
         // A self-referencing IteratorAggregate must not cause the sandbox policy
         // walker to recurse infinitely when materialising the iterable. PHP itself
@@ -1554,7 +1554,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSourcePolicySandboxBlocksToStringInTraversableJoin()
+    public function testSourcePolicySandboxBlocksToStringInTraversableJoin(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -1580,7 +1580,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSourcePolicySandboxBlocksToStringInTraversableReplace()
+    public function testSourcePolicySandboxBlocksToStringInTraversableReplace(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -1602,7 +1602,7 @@ EOF
         }
     }
 
-    public function testSandboxPreservesTraversableArgumentIdentity()
+    public function testSandboxPreservesTraversableArgumentIdentity(): void
     {
         // Regression for https://github.com/twigphp/Twig/issues/4820:
         // a typed Traversable argument (e.g. Symfony's FormView) must reach
@@ -1630,7 +1630,7 @@ EOF
         $this->assertSame('stringable-traversable', $twig->load('index')->render($params));
     }
 
-    public function testSandboxStillBlocksDisallowedToStringInTraversableArgument()
+    public function testSandboxStillBlocksDisallowedToStringInTraversableArgument(): void
     {
         // The container is returned as-is, but yielded elements must still
         // be policy-checked since host code can string-coerce them.
@@ -1883,7 +1883,7 @@ EOF
         $this->assertSame('ok', $twig->load('index')->render(['n' => 42]));
     }
 
-    public function testColumnFilterUnaffectedOutsideSandbox()
+    public function testColumnFilterUnaffectedOutsideSandbox(): void
     {
         $params = ['obj' => new ColumnObject()];
         $twig = $this->getEnvironment(false, [], ['index' => "{{ [obj]|column('bar')|first }}"]);
@@ -1895,7 +1895,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSourcePolicySandboxBlocksColumnFilterOnDisallowedProperty()
+    public function testSourcePolicySandboxBlocksColumnFilterOnDisallowedProperty(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -1922,7 +1922,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSourcePolicySandboxBlocksColumnFilterOnDisallowedIndex()
+    public function testSourcePolicySandboxBlocksColumnFilterOnDisallowedIndex(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -1949,7 +1949,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSourcePolicySandboxAllowsColumnFilterOnAllowedProperty()
+    public function testSourcePolicySandboxAllowsColumnFilterOnAllowedProperty(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -1970,7 +1970,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSourcePolicySandboxBlocksColumnFilterOnMagicGetter()
+    public function testSourcePolicySandboxBlocksColumnFilterOnMagicGetter(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -2008,7 +2008,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSandboxSourcePolicyEnableReturningFalse()
+    public function testSandboxSourcePolicyEnableReturningFalse(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -2025,7 +2025,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSandboxSourcePolicyEnableReturningTrue()
+    public function testSandboxSourcePolicyEnableReturningTrue(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -2043,7 +2043,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSandboxSourcePolicyFalseDoesntOverrideOtherEnables()
+    public function testSandboxSourcePolicyFalseDoesntOverrideOtherEnables(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -2063,7 +2063,7 @@ EOF
      * @dataProvider provideSourcePolicyArrowBlockedTemplates
      */
     #[DataProvider('provideSourcePolicyArrowBlockedTemplates'), Group('legacy')]
-    public function testSourcePolicyBlocksNonClosureCallableInArrow(string $template)
+    public function testSourcePolicyBlocksNonClosureCallableInArrow(string $template): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -2096,7 +2096,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testSourcePolicyAllowsClosureInArrow()
+    public function testSourcePolicyAllowsClosureInArrow(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -2115,7 +2115,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testNonSandboxedSourcePolicyAllowsNonClosureCallable()
+    public function testNonSandboxedSourcePolicyAllowsNonClosureCallable(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
         $this->expectDeprecation('Since twig/twig 3.15: Passing a callable that is not a PHP \Closure as an argument to the "sort" filter is deprecated.');
@@ -2131,7 +2131,7 @@ EOF
         $this->assertSame('a,b', $twig->load('1_basic')->render([]));
     }
 
-    public function testNeedsIsSandboxedFilterReceivesTrueWhenSandboxed()
+    public function testNeedsIsSandboxedFilterReceivesTrueWhenSandboxed(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ "foo"|sandbox_aware }}'], [], ['sandbox_aware']);
         $twig->addFilter(new TwigFilter('sandbox_aware', static function (bool $isSandboxed, string $value) {
@@ -2141,7 +2141,7 @@ EOF
         $this->assertSame('foo:on', $twig->load('index')->render([]));
     }
 
-    public function testNeedsIsSandboxedFilterReceivesFalseWhenNotSandboxed()
+    public function testNeedsIsSandboxedFilterReceivesFalseWhenNotSandboxed(): void
     {
         $twig = $this->getEnvironment(false, [], ['index' => '{{ "foo"|sandbox_aware }}']);
         $twig->addFilter(new TwigFilter('sandbox_aware', static function (bool $isSandboxed, string $value) {
@@ -2155,7 +2155,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testNeedsIsSandboxedFilterFollowsSourcePolicy()
+    public function testNeedsIsSandboxedFilterFollowsSourcePolicy(): void
     {
         $this->expectDeprecation('Since twig/twig 3.27.0: The "Twig\Sandbox\SourcePolicyInterface" interface is deprecated with no replacement, do not pass an instance to "Twig\Extension\SandboxExtension".');
 
@@ -2176,7 +2176,7 @@ EOF
         $this->assertSame('foo:off', $twig->load('out')->render([]));
     }
 
-    public function testNeedsIsSandboxedFunctionWithoutSandboxExtension()
+    public function testNeedsIsSandboxedFunctionWithoutSandboxExtension(): void
     {
         $loader = new ArrayLoader(['index' => '{{ sandbox_aware("foo") }}']);
         $twig = new Environment($loader, ['debug' => true, 'cache' => false, 'autoescape' => false]);
@@ -2187,7 +2187,7 @@ EOF
         $this->assertSame('foo:off', $twig->load('index')->render([]));
     }
 
-    public function testNeedsIsSandboxedTestReceivesTrueWhenSandboxed()
+    public function testNeedsIsSandboxedTestReceivesTrueWhenSandboxed(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ "foo" is sandbox_aware ? "on" : "off" }}'], [], [], [], [], [], null, false, ['sandbox_aware']);
         $twig->addTest(new TwigTest('sandbox_aware', static function (bool $isSandboxed, string $value) {
@@ -2197,7 +2197,7 @@ EOF
         $this->assertSame('on', $twig->load('index')->render([]));
     }
 
-    public function testNeedsIsSandboxedTestReceivesFalseWhenNotSandboxed()
+    public function testNeedsIsSandboxedTestReceivesFalseWhenNotSandboxed(): void
     {
         $twig = $this->getEnvironment(false, [], ['index' => '{{ "foo" is sandbox_aware ? "on" : "off" }}']);
         $twig->addTest(new TwigTest('sandbox_aware', static function (bool $isSandboxed, string $value) {
@@ -2211,7 +2211,7 @@ EOF
      * @group legacy
      */
     #[Group('legacy')]
-    public function testNeedsIsSandboxedHelperTriggersDeprecationForCustomImplementation()
+    public function testNeedsIsSandboxedHelperTriggersDeprecationForCustomImplementation(): void
     {
         $callable = new LegacyTwigCallableWithoutNeedsIsSandboxed();
 
@@ -2220,7 +2220,7 @@ EOF
         $this->assertFalse(CallExpression::needsIsSandboxed($callable));
     }
 
-    public function testAlwaysAllowedInSandboxFilterBypassesAllowList()
+    public function testAlwaysAllowedInSandboxFilterBypassesAllowList(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ "fabien"|safe_upper }}']);
         $twig->addFilter(new TwigFilter('safe_upper', 'strtoupper', ['always_allowed_in_sandbox' => true]));
@@ -2228,7 +2228,7 @@ EOF
         $this->assertSame('FABIEN', $twig->load('index')->render([]));
     }
 
-    public function testAlwaysAllowedInSandboxFilterStillEnforcedWhenFlagNotSet()
+    public function testAlwaysAllowedInSandboxFilterStillEnforcedWhenFlagNotSet(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ "fabien"|gated_upper }}']);
         $twig->addFilter(new TwigFilter('gated_upper', 'strtoupper'));
@@ -2238,7 +2238,7 @@ EOF
         $twig->load('index')->render([]);
     }
 
-    public function testAlwaysAllowedInSandboxFunctionBypassesAllowList()
+    public function testAlwaysAllowedInSandboxFunctionBypassesAllowList(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ safe_greet("fabien") }}']);
         $twig->addFunction(new TwigFunction('safe_greet', static fn (string $name) => "hi $name", ['always_allowed_in_sandbox' => true]));
@@ -2246,7 +2246,7 @@ EOF
         $this->assertSame('hi fabien', $twig->load('index')->render([]));
     }
 
-    public function testAlwaysAllowedInSandboxFunctionStillEnforcedWhenFlagNotSet()
+    public function testAlwaysAllowedInSandboxFunctionStillEnforcedWhenFlagNotSet(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ gated_greet("fabien") }}']);
         $twig->addFunction(new TwigFunction('gated_greet', static fn (string $name) => "hi $name"));
@@ -2256,7 +2256,7 @@ EOF
         $twig->load('index')->render([]);
     }
 
-    public function testAlwaysAllowedInSandboxTestBypassesAllowList()
+    public function testAlwaysAllowedInSandboxTestBypassesAllowList(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ 4 is safe_even ? "yes" : "no" }}'], [], [], [], [], [], null, true);
         $twig->addTest(new TwigTest('safe_even', static fn ($value) => 0 === $value % 2, ['always_allowed_in_sandbox' => true]));
@@ -2264,7 +2264,7 @@ EOF
         $this->assertSame('yes', $twig->load('index')->render([]));
     }
 
-    public function testAlwaysAllowedInSandboxTestStillEnforcedWhenFlagNotSet()
+    public function testAlwaysAllowedInSandboxTestStillEnforcedWhenFlagNotSet(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ 4 is gated_even ? "yes" : "no" }}'], [], [], [], [], [], null, true);
         $twig->addTest(new TwigTest('gated_even', static fn ($value) => 0 === $value % 2));
@@ -2274,7 +2274,7 @@ EOF
         $twig->load('index')->render([]);
     }
 
-    public function testAlwaysAllowedInSandboxFunctionAlsoCoversRangeOperator()
+    public function testAlwaysAllowedInSandboxFunctionAlsoCoversRangeOperator(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ (1..2)[0] }}']);
         // override the built-in `range` function with one that is always allowed
@@ -2283,7 +2283,7 @@ EOF
         $this->assertSame('1', $twig->load('index')->render([]));
     }
 
-    public function testAlwaysAllowedInSandboxFilterFromUndefinedCallbackUsesParsedCallable()
+    public function testAlwaysAllowedInSandboxFilterFromUndefinedCallbackUsesParsedCallable(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ "fabien"|callback_upper }}']);
         $callbackCalled = false;
@@ -2299,7 +2299,7 @@ EOF
         $this->assertSame('FABIEN', $twig->load('index')->render([]));
     }
 
-    public function testAlwaysAllowedInSandboxFunctionFromUndefinedCallbackUsesParsedCallable()
+    public function testAlwaysAllowedInSandboxFunctionFromUndefinedCallbackUsesParsedCallable(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ callback_upper("fabien") }}']);
         $callbackCalled = false;
@@ -2315,7 +2315,7 @@ EOF
         $this->assertSame('FABIEN', $twig->load('index')->render([]));
     }
 
-    public function testAlwaysAllowedInSandboxParserCallableFunctionFromUndefinedCallbackUsesParsedCallable()
+    public function testAlwaysAllowedInSandboxParserCallableFunctionFromUndefinedCallbackUsesParsedCallable(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ callback_literal() }}']);
         $callbackCalled = false;
@@ -2334,7 +2334,7 @@ EOF
         $this->assertSame('literal', $twig->load('index')->render([]));
     }
 
-    public function testAlwaysAllowedInSandboxTagBypassesAllowList()
+    public function testAlwaysAllowedInSandboxTagBypassesAllowList(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{% always_allowed_tag %}']);
         $twig->addTokenParser(new AlwaysAllowedSandboxTokenParser());
@@ -2342,7 +2342,7 @@ EOF
         $this->assertSame('always-allowed', $twig->load('index')->render([]));
     }
 
-    public function testAlwaysAllowedInSandboxTagStillEnforcedWhenFlagNotSet()
+    public function testAlwaysAllowedInSandboxTagStillEnforcedWhenFlagNotSet(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{% gated_tag %}']);
         $twig->addTokenParser(new GatedSandboxTokenParser());
@@ -2352,7 +2352,7 @@ EOF
         $twig->load('index')->render([]);
     }
 
-    public function testAlwaysAllowedInSandboxFilterStillEnforcesToStringPolicyOnArguments()
+    public function testAlwaysAllowedInSandboxFilterStillEnforcesToStringPolicyOnArguments(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ obj|safe_upper }}']);
         $twig->addFilter(new TwigFilter('safe_upper', static fn (string $s) => strtoupper($s), ['always_allowed_in_sandbox' => true]));
@@ -2362,7 +2362,7 @@ EOF
         $twig->load('index')->render(['obj' => new FooObject()]);
     }
 
-    public function testAlwaysAllowedInSandboxFunctionStillEnforcesToStringPolicyOnArguments()
+    public function testAlwaysAllowedInSandboxFunctionStillEnforcesToStringPolicyOnArguments(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{{ safe_greet(obj) }}']);
         $twig->addFunction(new TwigFunction('safe_greet', static fn (string $s) => "hi $s", ['always_allowed_in_sandbox' => true]));
@@ -2375,7 +2375,7 @@ EOF
     /**
      * @group legacy
      */
-    public function testCustomTokenParserWithoutIsAlwaysAllowedInSandboxTriggersDeprecation()
+    public function testCustomTokenParserWithoutIsAlwaysAllowedInSandboxTriggersDeprecation(): void
     {
         $twig = $this->getEnvironment(true, [], ['index' => '{% legacy_tag %}'], tags: ['legacy_tag']);
         $twig->addTokenParser(new LegacyTokenParserWithoutIsAlwaysAllowedInSandbox());
@@ -2477,13 +2477,13 @@ class LegacyTwigCallableWithoutNeedsIsSandboxed implements TwigCallableInterface
 
 class ParentClass
 {
-    public function ParentMethod()
+    public function ParentMethod(): void
     {
     }
 }
 class ChildClass extends ParentClass
 {
-    public function ChildMethod()
+    public function ChildMethod(): void
     {
     }
 }
@@ -2494,7 +2494,7 @@ class FooObject
 
     public $bar = 'bar';
 
-    public static function reset()
+    public static function reset(): void
     {
         self::$called = ['__toString' => 0, 'foo' => 0, 'getFooBar' => 0];
     }
diff --git a/tests/Extension/StringLoaderExtensionTest.php b/tests/Extension/StringLoaderExtensionTest.php
index b49e7bfbb..fe3ea17a2 100644
--- a/tests/Extension/StringLoaderExtensionTest.php
+++ b/tests/Extension/StringLoaderExtensionTest.php
@@ -19,7 +19,7 @@ use Twig\Loader\ArrayLoader;
 
 class StringLoaderExtensionTest extends TestCase
 {
-    public function testIncludeWithTemplateStringAndNoSandbox()
+    public function testIncludeWithTemplateStringAndNoSandbox(): void
     {
         $twig = new Environment(new ArrayLoader());
         $twig->addExtension(new StringLoaderExtension());
diff --git a/tests/FactoryRuntimeLoaderTest.php b/tests/FactoryRuntimeLoaderTest.php
index 33066886f..08d277a64 100644
--- a/tests/FactoryRuntimeLoaderTest.php
+++ b/tests/FactoryRuntimeLoaderTest.php
@@ -25,14 +25,14 @@ use Twig\RuntimeLoader\FactoryRuntimeLoader;
 
 class FactoryRuntimeLoaderTest extends TestCase
 {
-    public function testLoad()
+    public function testLoad(): void
     {
         $loader = new FactoryRuntimeLoader(['stdClass' => '\Twig\Tests\getRuntime']);
 
         $this->assertInstanceOf('stdClass', $loader->load('stdClass'));
     }
 
-    public function testLoadReturnsNullForUnmappedRuntime()
+    public function testLoadReturnsNullForUnmappedRuntime(): void
     {
         $loader = new FactoryRuntimeLoader();
 
diff --git a/tests/FileExtensionEscapingStrategyTest.php b/tests/FileExtensionEscapingStrategyTest.php
index 75eb6c56e..301c9a4c1 100644
--- a/tests/FileExtensionEscapingStrategyTest.php
+++ b/tests/FileExtensionEscapingStrategyTest.php
@@ -30,7 +30,7 @@ class FileExtensionEscapingStrategyTest extends TestCase
      * @dataProvider getGuessData
      */
     #[DataProvider('getGuessData')]
-    public function testGuess($strategy, $filename)
+    public function testGuess($strategy, $filename): void
     {
         $this->assertSame($strategy, FileExtensionEscapingStrategy::guess($filename));
     }
diff --git a/tests/FilesystemHelper.php b/tests/FilesystemHelper.php
index ce7cf7154..31152c132 100644
--- a/tests/FilesystemHelper.php
+++ b/tests/FilesystemHelper.php
@@ -22,7 +22,7 @@ namespace Twig\Tests;
 
 class FilesystemHelper
 {
-    public static function removeDir($dir)
+    public static function removeDir($dir): void
     {
         $iterator = new \RecursiveIteratorIterator(new \RecursiveDirectoryIterator($dir, \FilesystemIterator::SKIP_DOTS), \RecursiveIteratorIterator::CHILD_FIRST);
         foreach ($iterator as $filename => $fileInfo) {
diff --git a/tests/IntegrationTest.php b/tests/IntegrationTest.php
index 8daf5aa43..41b8373a6 100644
--- a/tests/IntegrationTest.php
+++ b/tests/IntegrationTest.php
@@ -365,7 +365,7 @@ class TwigTestExtension extends AbstractExtension
  */
 class MagicCallStub
 {
-    public function __call($name, $args)
+    public function __call($name, $args): void
     {
         throw new \Exception('__call shall not be called.');
     }
diff --git a/tests/LexerTest.php b/tests/LexerTest.php
index 90b1c3363..79ccbeabf 100644
--- a/tests/LexerTest.php
+++ b/tests/LexerTest.php
@@ -35,7 +35,7 @@ class LexerTest extends TestCase
 {
     use ExpectDeprecationTrait;
 
-    public function testNameLabelForTag()
+    public function testNameLabelForTag(): void
     {
         $template = '{% § %}';
 
@@ -46,7 +46,7 @@ class LexerTest extends TestCase
         $this->assertSame('§', $stream->expect(Token::NAME_TYPE)->getValue());
     }
 
-    public function testNameLabelForFunction()
+    public function testNameLabelForFunction(): void
     {
         $template = '{{ §() }}';
 
@@ -57,7 +57,7 @@ class LexerTest extends TestCase
         $this->assertSame('§', $stream->expect(Token::NAME_TYPE)->getValue());
     }
 
-    public function testBracketsNesting()
+    public function testBracketsNesting(): void
     {
         $template = '{{ {"a":{"b":"c"}} }}';
 
@@ -83,7 +83,7 @@ class LexerTest extends TestCase
         return $count;
     }
 
-    public function testLineDirective()
+    public function testLineDirective(): void
     {
         $template = "foo\n"
             ."bar\n"
@@ -105,7 +105,7 @@ class LexerTest extends TestCase
         $this->assertSame(12, $stream->expect(Token::NAME_TYPE)->getLine());
     }
 
-    public function testLineDirectiveInline()
+    public function testLineDirectiveInline(): void
     {
         $template = "foo\n"
             ."bar{% line 10 %}{{\n"
@@ -123,7 +123,7 @@ class LexerTest extends TestCase
         $this->assertSame(11, $stream->expect(Token::NAME_TYPE)->getLine());
     }
 
-    public function testLongComments()
+    public function testLongComments(): void
     {
         $template = '{# '.str_repeat('*', 100000).' #}';
 
@@ -135,7 +135,7 @@ class LexerTest extends TestCase
         $this->addToAssertionCount(1);
     }
 
-    public function testLongVerbatim()
+    public function testLongVerbatim(): void
     {
         $template = '{% verbatim %}'.str_repeat('*', 100000).'{% endverbatim %}';
 
@@ -147,7 +147,7 @@ class LexerTest extends TestCase
         $this->addToAssertionCount(1);
     }
 
-    public function testLongVar()
+    public function testLongVar(): void
     {
         $template = '{{ '.str_repeat('x', 100000).' }}';
 
@@ -159,7 +159,7 @@ class LexerTest extends TestCase
         $this->addToAssertionCount(1);
     }
 
-    public function testLongBlock()
+    public function testLongBlock(): void
     {
         $template = '{% '.str_repeat('x', 100000).' %}';
 
@@ -171,7 +171,7 @@ class LexerTest extends TestCase
         $this->addToAssertionCount(1);
     }
 
-    public function testBigNumbers()
+    public function testBigNumbers(): void
     {
         $template = '{{ 922337203685477580700 }}';
 
@@ -186,7 +186,7 @@ class LexerTest extends TestCase
      * @dataProvider getStringWithEscapedDelimiter
      */
     #[DataProvider('getStringWithEscapedDelimiter')]
-    public function testStringWithEscapedDelimiter(string $template, string $expected)
+    public function testStringWithEscapedDelimiter(string $template, string $expected): void
     {
         $lexer = new Lexer(new Environment(new ArrayLoader()));
         $stream = $lexer->tokenize(new Source($template, 'index'));
@@ -275,7 +275,7 @@ class LexerTest extends TestCase
      * @dataProvider getStringWithEscapedDelimiterProducingDeprecation
      */
     #[DataProvider('getStringWithEscapedDelimiterProducingDeprecation'), Group('legacy')]
-    public function testStringWithEscapedDelimiterProducingDeprecation(string $template, string $expected, string $expectedDeprecation)
+    public function testStringWithEscapedDelimiterProducingDeprecation(string $template, string $expected, string $expectedDeprecation): void
     {
         $this->expectDeprecation($expectedDeprecation);
 
@@ -316,7 +316,7 @@ class LexerTest extends TestCase
         ];
     }
 
-    public function testStringWithInterpolation()
+    public function testStringWithInterpolation(): void
     {
         $template = 'foo {{ "bar #{ baz + 1 }" }}';
 
@@ -337,7 +337,7 @@ class LexerTest extends TestCase
         $this->addToAssertionCount(1);
     }
 
-    public function testStringWithEscapedInterpolation()
+    public function testStringWithEscapedInterpolation(): void
     {
         $template = '{{ "bar \#{baz+1}" }}';
 
@@ -352,7 +352,7 @@ class LexerTest extends TestCase
         $this->addToAssertionCount(1);
     }
 
-    public function testStringWithHash()
+    public function testStringWithHash(): void
     {
         $template = '{{ "bar # baz" }}';
 
@@ -367,7 +367,7 @@ class LexerTest extends TestCase
         $this->addToAssertionCount(1);
     }
 
-    public function testStringWithUnterminatedInterpolation()
+    public function testStringWithUnterminatedInterpolation(): void
     {
         $template = '{{ "bar #{x" }}';
         $lexer = new Lexer(new Environment(new ArrayLoader()));
@@ -378,7 +378,7 @@ class LexerTest extends TestCase
         $lexer->tokenize(new Source($template, 'index'));
     }
 
-    public function testStringWithNestedInterpolations()
+    public function testStringWithNestedInterpolations(): void
     {
         $template = '{{ "bar #{ "foo#{bar}" }" }}';
 
@@ -399,7 +399,7 @@ class LexerTest extends TestCase
         $this->addToAssertionCount(1);
     }
 
-    public function testStringWithNestedInterpolationsInBlock()
+    public function testStringWithNestedInterpolationsInBlock(): void
     {
         $template = '{% foo "bar #{ "foo#{bar}" }" %}';
 
@@ -421,7 +421,7 @@ class LexerTest extends TestCase
         $this->addToAssertionCount(1);
     }
 
-    public function testOperatorEndingWithALetterAtTheEndOfALine()
+    public function testOperatorEndingWithALetterAtTheEndOfALine(): void
     {
         $template = "{{ 1 and\n0}}";
 
@@ -436,7 +436,7 @@ class LexerTest extends TestCase
         $this->addToAssertionCount(1);
     }
 
-    public function testFilterAndAttributeNamedAfterOperator()
+    public function testFilterAndAttributeNamedAfterOperator(): void
     {
         // Ensure that filters/attributes aren't mistaken for operators when their names conflict
         // (see https://github.com/twigphp/Twig/issues/4767)
@@ -472,7 +472,7 @@ class LexerTest extends TestCase
         // can be executed without throwing any exceptions
     }
 
-    public function testLiteralIsNotAnOperator()
+    public function testLiteralIsNotAnOperator(): void
     {
         // "literal" is the name of the LiteralExpressionParser but should not be treated as an operator token
         $template = '{{ literal }}';
@@ -486,7 +486,7 @@ class LexerTest extends TestCase
         $this->addToAssertionCount(1);
     }
 
-    public function testUnterminatedVariable()
+    public function testUnterminatedVariable(): void
     {
         $template = '
 
@@ -504,7 +504,7 @@ bar
         $lexer->tokenize(new Source($template, 'index'));
     }
 
-    public function testUnterminatedBlock()
+    public function testUnterminatedBlock(): void
     {
         $template = '
 
@@ -523,7 +523,7 @@ bar
         $lexer->tokenize(new Source($template, 'index'));
     }
 
-    public function testOverridingSyntax()
+    public function testOverridingSyntax(): void
     {
         $template = '[# comment #]{# variable #}/# if true #/true/# endif #/';
         $lexer = new Lexer(new Environment(new ArrayLoader()), [
@@ -553,7 +553,7 @@ bar
      * @dataProvider getTemplateForErrorsAtTheEndOfTheStream
      */
     #[DataProvider('getTemplateForErrorsAtTheEndOfTheStream')]
-    public function testErrorsAtTheEndOfTheStream(string $template)
+    public function testErrorsAtTheEndOfTheStream(string $template): void
     {
         $lexer = new Lexer(new Environment(new ArrayLoader()));
         set_error_handler(function () {
@@ -577,7 +577,7 @@ bar
      * @dataProvider getTemplateForStrings
      */
     #[DataProvider('getTemplateForStrings')]
-    public function testStrings(string $expected)
+    public function testStrings(string $expected): void
     {
         $template = '{{ "'.$expected.'" }}';
         $lexer = new Lexer(new Environment(new ArrayLoader()));
@@ -602,7 +602,7 @@ bar
         yield ['في العالم العربي، يُعتبر الخط العربي أحد أجمل أشكال الفن. يُستخدم الخط في تزيين المساجد والكتب والمخطوطات القديمة. يتميز الخط العربي بجماله وتناسقه، ويُعتبر رمزًا للثقافة الإسلامية.'];
     }
 
-    public function testInlineCommentWithHashInString()
+    public function testInlineCommentWithHashInString(): void
     {
         $lexer = new Lexer(new Environment(new ArrayLoader()));
         $stream = $lexer->tokenize(new Source('{{ "me # this is NOT an inline comment" }}', 'index'));
@@ -616,7 +616,7 @@ bar
      * @dataProvider getTemplateForInlineCommentsForVariable
      */
     #[DataProvider('getTemplateForInlineCommentsForVariable')]
-    public function testInlineCommentForVariable(string $template)
+    public function testInlineCommentForVariable(string $template): void
     {
         $lexer = new Lexer(new Environment(new ArrayLoader()));
         $stream = $lexer->tokenize(new Source($template, 'index'));
@@ -650,7 +650,7 @@ bar
      * @dataProvider getTemplateForInlineCommentsForBlock
      */
     #[DataProvider('getTemplateForInlineCommentsForBlock')]
-    public function testInlineCommentForBlock(string $template)
+    public function testInlineCommentForBlock(string $template): void
     {
         $lexer = new Lexer(new Environment(new ArrayLoader()));
         $stream = $lexer->tokenize(new Source($template, 'index'));
@@ -689,7 +689,7 @@ bar
      * @dataProvider getTemplateForInlineCommentsForComment
      */
     #[DataProvider('getTemplateForInlineCommentsForComment')]
-    public function testInlineCommentForComment(string $template)
+    public function testInlineCommentForComment(string $template): void
     {
         $lexer = new Lexer(new Environment(new ArrayLoader()));
         $stream = $lexer->tokenize(new Source($template, 'index'));
@@ -707,7 +707,7 @@ bar
      * @dataProvider getTemplateForUnclosedBracketInExpression
      */
     #[DataProvider('getTemplateForUnclosedBracketInExpression')]
-    public function testUnclosedBracketInExpression(string $template, string $bracket)
+    public function testUnclosedBracketInExpression(string $template, string $bracket): void
     {
         $lexer = new Lexer(new Environment(new ArrayLoader()));
 
@@ -729,7 +729,7 @@ bar
      * @dataProvider getTemplateForUnexpectedBracketInExpression
      */
     #[DataProvider('getTemplateForUnexpectedBracketInExpression')]
-    public function testUnexpectedBracketInExpression(string $template, string $bracket, int $column)
+    public function testUnexpectedBracketInExpression(string $template, string $bracket, int $column): void
     {
         $lexer = new Lexer(new Environment(new ArrayLoader()));
 
@@ -747,7 +747,7 @@ bar
         yield ['{{ ([1] + 3)) }}', ')', 13];
     }
 
-    public function testTokensCarryTheirSourceOffset()
+    public function testTokensCarryTheirSourceOffset(): void
     {
         $template = 'Hello {{ name }}!';
 
@@ -775,7 +775,7 @@ bar
         }
     }
 
-    public function testOffsetsAllowRecoveringTheRawExpressionSource()
+    public function testOffsetsAllowRecoveringTheRawExpressionSource(): void
     {
         $template = "Hello {{ name|upper ~ '!' }}";
 
@@ -795,7 +795,7 @@ bar
         $this->assertSame("name|upper ~ '!'", $raw);
     }
 
-    public function testOffsetsReferToTheOriginalSourceWhenLineEndingsAreNormalized()
+    public function testOffsetsReferToTheOriginalSourceWhenLineEndingsAreNormalized(): void
     {
         $template = "Hello\r\n{{ name }}";
 
@@ -813,7 +813,7 @@ bar
         $this->assertSame('name', trim(substr($template, $start + 2, $end - $start - 2)));
     }
 
-    public function testBlockTagDelimitersPointAtTheMarkers()
+    public function testBlockTagDelimitersPointAtTheMarkers(): void
     {
         $template = '{% set x = 1 %}';
 
@@ -831,7 +831,7 @@ bar
         $this->assertSame('%}', substr($template, $end, 2));
     }
 
-    public function testClosingDelimiterLineMatchesTheMarkerLine()
+    public function testClosingDelimiterLineMatchesTheMarkerLine(): void
     {
         $template = "{% from 'forms.twig'\n  %}";
         $env = new Environment(new ArrayLoader());
@@ -846,12 +846,12 @@ bar
         }
     }
 
-    public function testSyntheticTokensHaveNoOffset()
+    public function testSyntheticTokensHaveNoOffset(): void
     {
         $this->assertNull((new Token(Token::NAME_TYPE, 'foo', 1))->getOffset());
     }
 
-    public function testSyntaxErrorReportsTheColumn()
+    public function testSyntaxErrorReportsTheColumn(): void
     {
         $lexer = new Lexer(new Environment(new ArrayLoader()));
 
@@ -865,7 +865,7 @@ bar
         }
     }
 
-    public function testSyntaxErrorColumnUsesOriginalSourceOffsets()
+    public function testSyntaxErrorColumnUsesOriginalSourceOffsets(): void
     {
         $template = "x\r\n{{ 1__2 }}";
         $env = new Environment(new ArrayLoader());
diff --git a/tests/Loader/ArrayTest.php b/tests/Loader/ArrayTest.php
index fd04dadb9..3cebb3ae7 100644
--- a/tests/Loader/ArrayTest.php
+++ b/tests/Loader/ArrayTest.php
@@ -26,7 +26,7 @@ use Twig\Loader\ArrayLoader;
 
 class ArrayTest extends TestCase
 {
-    public function testGetSourceContextWhenTemplateDoesNotExist()
+    public function testGetSourceContextWhenTemplateDoesNotExist(): void
     {
         $loader = new ArrayLoader();
 
@@ -34,14 +34,14 @@ class ArrayTest extends TestCase
         $loader->getSourceContext('foo');
     }
 
-    public function testGetCacheKey()
+    public function testGetCacheKey(): void
     {
         $loader = new ArrayLoader(['foo' => 'bar']);
 
         $this->assertEquals('foo:bar', $loader->getCacheKey('foo'));
     }
 
-    public function testGetCacheKeyWhenTemplateHasDuplicateContent()
+    public function testGetCacheKeyWhenTemplateHasDuplicateContent(): void
     {
         $loader = new ArrayLoader([
             'foo' => 'bar',
@@ -52,7 +52,7 @@ class ArrayTest extends TestCase
         $this->assertEquals('baz:bar', $loader->getCacheKey('baz'));
     }
 
-    public function testGetCacheKeyIsProtectedFromEdgeCollisions()
+    public function testGetCacheKeyIsProtectedFromEdgeCollisions(): void
     {
         $loader = new ArrayLoader([
             'foo__' => 'bar',
@@ -63,7 +63,7 @@ class ArrayTest extends TestCase
         $this->assertEquals('foo:__bar', $loader->getCacheKey('foo'));
     }
 
-    public function testGetCacheKeyWhenTemplateDoesNotExist()
+    public function testGetCacheKeyWhenTemplateDoesNotExist(): void
     {
         $loader = new ArrayLoader();
 
@@ -71,7 +71,7 @@ class ArrayTest extends TestCase
         $loader->getCacheKey('foo');
     }
 
-    public function testSetTemplate()
+    public function testSetTemplate(): void
     {
         $loader = new ArrayLoader();
         $loader->setTemplate('foo', 'bar');
@@ -79,13 +79,13 @@ class ArrayTest extends TestCase
         $this->assertEquals('bar', $loader->getSourceContext('foo')->getCode());
     }
 
-    public function testIsFresh()
+    public function testIsFresh(): void
     {
         $loader = new ArrayLoader(['foo' => 'bar']);
         $this->assertTrue($loader->isFresh('foo', time()));
     }
 
-    public function testIsFreshWhenTemplateDoesNotExist()
+    public function testIsFreshWhenTemplateDoesNotExist(): void
     {
         $loader = new ArrayLoader();
 
diff --git a/tests/Loader/ChainTest.php b/tests/Loader/ChainTest.php
index 473ba768d..6519cbb9d 100644
--- a/tests/Loader/ChainTest.php
+++ b/tests/Loader/ChainTest.php
@@ -29,7 +29,7 @@ use Twig\Loader\LoaderInterface;
 
 class ChainTest extends TestCase
 {
-    public function testGetSourceContext()
+    public function testGetSourceContext(): void
     {
         $path = __DIR__.'/../Fixtures';
         $loader = new ChainLoader([
@@ -50,7 +50,7 @@ class ChainTest extends TestCase
         $this->assertNotEquals('baz', $loader->getSourceContext('errors/base.html')->getCode());
     }
 
-    public function testGetSourceContextWhenTemplateDoesNotExist()
+    public function testGetSourceContextWhenTemplateDoesNotExist(): void
     {
         $loader = new ChainLoader([]);
 
@@ -58,7 +58,7 @@ class ChainTest extends TestCase
         $loader->getSourceContext('foo');
     }
 
-    public function testGetCacheKey()
+    public function testGetCacheKey(): void
     {
         $loader = new ChainLoader([
             new ArrayLoader(['foo' => 'bar']),
@@ -69,7 +69,7 @@ class ChainTest extends TestCase
         $this->assertEquals('bar:foo', $loader->getCacheKey('bar'));
     }
 
-    public function testGetCacheKeyWhenTemplateDoesNotExist()
+    public function testGetCacheKeyWhenTemplateDoesNotExist(): void
     {
         $loader = new ChainLoader([]);
 
@@ -77,7 +77,7 @@ class ChainTest extends TestCase
         $loader->getCacheKey('foo');
     }
 
-    public function testAddLoader()
+    public function testAddLoader(): void
     {
         $fooLoader = new ArrayLoader(['foo' => 'foo:code']);
         $barLoader = new ArrayLoader(['bar' => 'bar:code']);
@@ -105,7 +105,7 @@ class ChainTest extends TestCase
         ], $loader->getLoaders());
     }
 
-    public function testExists()
+    public function testExists(): void
     {
         $loader1 = $this->createMock(LoaderInterface::class);
         $loader1->expects($this->once())->method('exists')->willReturn(false);
diff --git a/tests/Loader/FilesystemTest.php b/tests/Loader/FilesystemTest.php
index f964afbc1..af3eff32b 100644
--- a/tests/Loader/FilesystemTest.php
+++ b/tests/Loader/FilesystemTest.php
@@ -28,7 +28,7 @@ use Twig\Loader\FilesystemLoader;
 
 class FilesystemTest extends TestCase
 {
-    public function testGetSourceContext()
+    public function testGetSourceContext(): void
     {
         $path = __DIR__.'/../Fixtures';
         $loader = new FilesystemLoader([$path]);
@@ -40,7 +40,7 @@ class FilesystemTest extends TestCase
      * @dataProvider getSecurityTests
      */
     #[DataProvider('getSecurityTests')]
-    public function testSecurity($template)
+    public function testSecurity($template): void
     {
         $loader = new FilesystemLoader([__DIR__.'/../Fixtures']);
         $loader->addPath(__DIR__.'/../Fixtures', 'foo');
@@ -86,7 +86,7 @@ class FilesystemTest extends TestCase
      * @dataProvider getBasePaths
      */
     #[DataProvider('getBasePaths')]
-    public function testPaths($basePath, $cacheKey, $rootPath)
+    public function testPaths($basePath, $cacheKey, $rootPath): void
     {
         $loader = new FilesystemLoader([$basePath.'/normal', $basePath.'/normal_bis'], $rootPath);
         $loader->setPaths([$basePath.'/named', $basePath.'/named_bis'], 'named');
@@ -148,13 +148,13 @@ class FilesystemTest extends TestCase
         ];
     }
 
-    public function testEmptyConstructor()
+    public function testEmptyConstructor(): void
     {
         $loader = new FilesystemLoader();
         $this->assertEquals([], $loader->getPaths());
     }
 
-    public function testGetNamespaces()
+    public function testGetNamespaces(): void
     {
         $loader = new FilesystemLoader(sys_get_temp_dir());
         $this->assertEquals([FilesystemLoader::MAIN_NAMESPACE], $loader->getNamespaces());
@@ -163,7 +163,7 @@ class FilesystemTest extends TestCase
         $this->assertEquals([FilesystemLoader::MAIN_NAMESPACE, 'named'], $loader->getNamespaces());
     }
 
-    public function testFindTemplateExceptionNamespace()
+    public function testFindTemplateExceptionNamespace(): void
     {
         $basePath = __DIR__.'/Fixtures';
 
@@ -178,7 +178,7 @@ class FilesystemTest extends TestCase
         }
     }
 
-    public function testFindTemplateWithCache()
+    public function testFindTemplateWithCache(): void
     {
         $basePath = __DIR__.'/Fixtures';
 
@@ -193,7 +193,7 @@ class FilesystemTest extends TestCase
         $this->assertEquals("path\n", $loader->getSourceContext('index.html')->getCode());
     }
 
-    public function testLoadTemplateAndRenderBlockWithCache()
+    public function testLoadTemplateAndRenderBlockWithCache(): void
     {
         $loader = new FilesystemLoader([]);
         $loader->addPath(__DIR__.'/Fixtures/themes/theme2');
@@ -222,7 +222,7 @@ class FilesystemTest extends TestCase
      * @dataProvider getArrayInheritanceTests
      */
     #[DataProvider('getArrayInheritanceTests')]
-    public function testArrayInheritance(string $templateName)
+    public function testArrayInheritance(string $templateName): void
     {
         $loader = new FilesystemLoader([]);
         $loader->addPath(__DIR__.'/Fixtures/inheritance');
@@ -233,7 +233,7 @@ class FilesystemTest extends TestCase
         $this->assertSame('VALID Child', $template->renderBlock('body', []));
     }
 
-    public function testLoadTemplateFromPhar()
+    public function testLoadTemplateFromPhar(): void
     {
         $loader = new FilesystemLoader([]);
         // phar-sample.phar was created with the following script:
@@ -243,7 +243,7 @@ class FilesystemTest extends TestCase
         $this->assertSame('hello from phar', $loader->getSourceContext('hello.twig')->getCode());
     }
 
-    public function testTemplateExistsAlwaysReturnsBool()
+    public function testTemplateExistsAlwaysReturnsBool(): void
     {
         $loader = new FilesystemLoader([]);
         $this->assertFalse($loader->exists("foo\0.twig"));
diff --git a/tests/Node/AutoEscapeTest.php b/tests/Node/AutoEscapeTest.php
index 18da5aae2..6608a71a7 100644
--- a/tests/Node/AutoEscapeTest.php
+++ b/tests/Node/AutoEscapeTest.php
@@ -27,7 +27,7 @@ use Twig\Test\NodeTestCase;
 
 class AutoEscapeTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $body = new Nodes([new TextNode('foo', 1)]);
         $node = new AutoEscapeNode(true, $body, 1);
diff --git a/tests/Node/BlockReferenceTest.php b/tests/Node/BlockReferenceTest.php
index 04a6b0ec3..50e8a61f2 100644
--- a/tests/Node/BlockReferenceTest.php
+++ b/tests/Node/BlockReferenceTest.php
@@ -25,7 +25,7 @@ use Twig\Test\NodeTestCase;
 
 class BlockReferenceTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $node = new BlockReferenceNode('foo', 1);
 
diff --git a/tests/Node/BlockTest.php b/tests/Node/BlockTest.php
index d5bf7037f..8606484ba 100644
--- a/tests/Node/BlockTest.php
+++ b/tests/Node/BlockTest.php
@@ -28,7 +28,7 @@ use Twig\Test\NodeTestCase;
 
 class BlockTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $body = new TextNode('foo', 1);
         $node = new BlockNode('foo', $body, 1);
diff --git a/tests/Node/DeprecatedTest.php b/tests/Node/DeprecatedTest.php
index 67dffabf8..5ae924270 100644
--- a/tests/Node/DeprecatedTest.php
+++ b/tests/Node/DeprecatedTest.php
@@ -35,7 +35,7 @@ use Twig\TwigFunction;
 
 class DeprecatedTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $expr = new ConstantExpression('foo', 1);
         $node = new DeprecatedNode($expr, 1);
@@ -99,6 +99,6 @@ EOF, $environment];
     }
 }
 
-function foo()
+function foo(): void
 {
 }
diff --git a/tests/Node/DoTest.php b/tests/Node/DoTest.php
index 34595109b..f5cfd3eba 100644
--- a/tests/Node/DoTest.php
+++ b/tests/Node/DoTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class DoTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $expr = new ConstantExpression('foo', 1);
         $node = new DoNode($expr, 1);
diff --git a/tests/Node/EmbedTest.php b/tests/Node/EmbedTest.php
index 13ff588d4..6a70f8df6 100644
--- a/tests/Node/EmbedTest.php
+++ b/tests/Node/EmbedTest.php
@@ -18,7 +18,7 @@ use Twig\Test\NodeTestCase;
 
 class EmbedTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $node = new EmbedNode('foo.twig', 0, null, false, false, 1);
 
diff --git a/tests/Node/Expression/ArrayTest.php b/tests/Node/Expression/ArrayTest.php
index 403a09202..03d44554a 100644
--- a/tests/Node/Expression/ArrayTest.php
+++ b/tests/Node/Expression/ArrayTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class ArrayTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $elements = [new ConstantExpression('foo', 1), $foo = new ConstantExpression('bar', 1)];
         $node = new ArrayExpression($elements, 1);
diff --git a/tests/Node/Expression/Binary/AddTest.php b/tests/Node/Expression/Binary/AddTest.php
index c249c2f55..c045fe3fb 100644
--- a/tests/Node/Expression/Binary/AddTest.php
+++ b/tests/Node/Expression/Binary/AddTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class AddTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $left = new ConstantExpression(1, 1);
         $right = new ConstantExpression(2, 1);
diff --git a/tests/Node/Expression/Binary/AndTest.php b/tests/Node/Expression/Binary/AndTest.php
index fc0ca9a50..156acd601 100644
--- a/tests/Node/Expression/Binary/AndTest.php
+++ b/tests/Node/Expression/Binary/AndTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class AndTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $left = new ConstantExpression(1, 1);
         $right = new ConstantExpression(2, 1);
diff --git a/tests/Node/Expression/Binary/ConcatTest.php b/tests/Node/Expression/Binary/ConcatTest.php
index 1d738bbd2..aab4ec99e 100644
--- a/tests/Node/Expression/Binary/ConcatTest.php
+++ b/tests/Node/Expression/Binary/ConcatTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class ConcatTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $left = new ConstantExpression(1, 1);
         $right = new ConstantExpression(2, 1);
diff --git a/tests/Node/Expression/Binary/DivTest.php b/tests/Node/Expression/Binary/DivTest.php
index 72aa644d2..2544a1c6f 100644
--- a/tests/Node/Expression/Binary/DivTest.php
+++ b/tests/Node/Expression/Binary/DivTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class DivTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $left = new ConstantExpression(1, 1);
         $right = new ConstantExpression(2, 1);
diff --git a/tests/Node/Expression/Binary/FloorDivTest.php b/tests/Node/Expression/Binary/FloorDivTest.php
index e27b5df57..bc4e31bec 100644
--- a/tests/Node/Expression/Binary/FloorDivTest.php
+++ b/tests/Node/Expression/Binary/FloorDivTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class FloorDivTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $left = new ConstantExpression(1, 1);
         $right = new ConstantExpression(2, 1);
diff --git a/tests/Node/Expression/Binary/ModTest.php b/tests/Node/Expression/Binary/ModTest.php
index 0897f3eb3..c325a3d4c 100644
--- a/tests/Node/Expression/Binary/ModTest.php
+++ b/tests/Node/Expression/Binary/ModTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class ModTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $left = new ConstantExpression(1, 1);
         $right = new ConstantExpression(2, 1);
diff --git a/tests/Node/Expression/Binary/MulTest.php b/tests/Node/Expression/Binary/MulTest.php
index 1f85b70cd..cb41f7917 100644
--- a/tests/Node/Expression/Binary/MulTest.php
+++ b/tests/Node/Expression/Binary/MulTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class MulTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $left = new ConstantExpression(1, 1);
         $right = new ConstantExpression(2, 1);
diff --git a/tests/Node/Expression/Binary/OrTest.php b/tests/Node/Expression/Binary/OrTest.php
index 6a555d295..347022aa1 100644
--- a/tests/Node/Expression/Binary/OrTest.php
+++ b/tests/Node/Expression/Binary/OrTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class OrTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $left = new ConstantExpression(1, 1);
         $right = new ConstantExpression(2, 1);
diff --git a/tests/Node/Expression/Binary/SubTest.php b/tests/Node/Expression/Binary/SubTest.php
index a74c8f745..c03f4272f 100644
--- a/tests/Node/Expression/Binary/SubTest.php
+++ b/tests/Node/Expression/Binary/SubTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class SubTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $left = new ConstantExpression(1, 1);
         $right = new ConstantExpression(2, 1);
diff --git a/tests/Node/Expression/CallTest.php b/tests/Node/Expression/CallTest.php
index 80a54ccab..eeef6e176 100644
--- a/tests/Node/Expression/CallTest.php
+++ b/tests/Node/Expression/CallTest.php
@@ -33,13 +33,13 @@ use Twig\TwigFunction;
 #[Group('legacy')]
 class CallTest extends TestCase
 {
-    public function testGetArguments()
+    public function testGetArguments(): void
     {
         $node = $this->createFunctionExpression('date', 'date');
         $this->assertEquals(['U', null], $this->getArguments($node, ['date', ['format' => 'U', 'timestamp' => null]]));
     }
 
-    public function testGetArgumentsWhenPositionalArgumentsAfterNamedArguments()
+    public function testGetArgumentsWhenPositionalArgumentsAfterNamedArguments(): void
     {
         $node = $this->createFunctionExpression('date', 'date');
 
@@ -49,7 +49,7 @@ class CallTest extends TestCase
         $this->getArguments($node, ['date', ['timestamp' => 123456, 'Y-m-d']]);
     }
 
-    public function testGetArgumentsWhenArgumentIsDefinedTwice()
+    public function testGetArgumentsWhenArgumentIsDefinedTwice(): void
     {
         $node = $this->createFunctionExpression('date', 'date');
 
@@ -59,7 +59,7 @@ class CallTest extends TestCase
         $this->getArguments($node, ['date', ['Y-m-d', 'format' => 'U']]);
     }
 
-    public function testGetArgumentsWithWrongNamedArgumentName()
+    public function testGetArgumentsWithWrongNamedArgumentName(): void
     {
         $node = $this->createFunctionExpression('date', 'date');
 
@@ -69,7 +69,7 @@ class CallTest extends TestCase
         $this->getArguments($node, ['date', ['Y-m-d', 'timestamp' => null, 'unknown' => '']]);
     }
 
-    public function testGetArgumentsWithWrongNamedArgumentNames()
+    public function testGetArgumentsWithWrongNamedArgumentNames(): void
     {
         $node = $this->createFunctionExpression('date', 'date');
 
@@ -79,7 +79,7 @@ class CallTest extends TestCase
         $this->getArguments($node, ['date', ['Y-m-d', 'timestamp' => null, 'unknown1' => '', 'unknown2' => '']]);
     }
 
-    public function testResolveArgumentsWithMissingValueForOptionalArgument()
+    public function testResolveArgumentsWithMissingValueForOptionalArgument(): void
     {
         if (\PHP_VERSION_ID >= 80000) {
             $this->markTestSkipped('substr_compare() has a default value in 8.0, so the test does not work anymore, one should find another PHP built-in function for this test to work in PHP 8.');
@@ -93,19 +93,19 @@ class CallTest extends TestCase
         $this->getArguments($node, ['substr_compare', ['abcd', 'bc', 'offset' => 1, 'case_sensitivity' => true]]);
     }
 
-    public function testResolveArgumentsOnlyNecessaryArgumentsForCustomFunction()
+    public function testResolveArgumentsOnlyNecessaryArgumentsForCustomFunction(): void
     {
         $node = $this->createFunctionExpression('custom_function', [$this, 'customFunction']);
         $this->assertEquals(['arg1'], $this->getArguments($node, [[$this, 'customFunction'], ['arg1' => 'arg1']]));
     }
 
-    public function testGetArgumentsForStaticMethod()
+    public function testGetArgumentsForStaticMethod(): void
     {
         $node = $this->createFunctionExpression('custom_static_function', __CLASS__.'::customStaticFunction');
         $this->assertEquals(['arg1'], $this->getArguments($node, [__CLASS__.'::customStaticFunction', ['arg1' => 'arg1']]));
     }
 
-    public function testResolveArgumentsWithMissingParameterForArbitraryArguments()
+    public function testResolveArgumentsWithMissingParameterForArbitraryArguments(): void
     {
         $node = $this->createFunctionExpression('foo', [$this, 'customFunctionWithArbitraryArguments'], true);
 
@@ -115,7 +115,7 @@ class CallTest extends TestCase
         $this->getArguments($node, [[$this, 'customFunctionWithArbitraryArguments'], []]);
     }
 
-    public function testGetArgumentsWithInvalidCallable()
+    public function testGetArgumentsWithInvalidCallable(): void
     {
         $node = $this->createFunctionExpression('foo', '<not-a-callable>', true);
 
@@ -125,7 +125,7 @@ class CallTest extends TestCase
         $this->getArguments($node, ['<not-a-callable>', []]);
     }
 
-    public function testResolveArgumentsWithMissingParameterForArbitraryArgumentsOnFunction()
+    public function testResolveArgumentsWithMissingParameterForArbitraryArgumentsOnFunction(): void
     {
         $node = $this->createFunctionExpression('foo', 'Twig\Tests\Node\Expression\custom_call_test_function', true);
 
@@ -135,7 +135,7 @@ class CallTest extends TestCase
         $this->getArguments($node, ['Twig\Tests\Node\Expression\custom_call_test_function', []]);
     }
 
-    public function testResolveArgumentsWithMissingParameterForArbitraryArgumentsOnObject()
+    public function testResolveArgumentsWithMissingParameterForArbitraryArgumentsOnObject(): void
     {
         $node = $this->createFunctionExpression('foo', new CallableTestClass(), true);
 
@@ -145,15 +145,15 @@ class CallTest extends TestCase
         $this->getArguments($node, [new CallableTestClass(), []]);
     }
 
-    public static function customStaticFunction($arg1, $arg2 = 'default', $arg3 = [])
+    public static function customStaticFunction($arg1, $arg2 = 'default', $arg3 = []): void
     {
     }
 
-    public function customFunction($arg1, $arg2 = 'default', $arg3 = [])
+    public function customFunction($arg1, $arg2 = 'default', $arg3 = []): void
     {
     }
 
-    public function customFunctionWithArbitraryArguments()
+    public function customFunctionWithArbitraryArguments(): void
     {
     }
 
@@ -176,11 +176,11 @@ class Node_Expression_Call extends FunctionExpression
 
 class CallableTestClass
 {
-    public function __invoke($required)
+    public function __invoke($required): void
     {
     }
 }
 
-function custom_call_test_function($required)
+function custom_call_test_function($required): void
 {
 }
diff --git a/tests/Node/Expression/ConditionalTest.php b/tests/Node/Expression/ConditionalTest.php
index b7ba8ff70..120b6317a 100644
--- a/tests/Node/Expression/ConditionalTest.php
+++ b/tests/Node/Expression/ConditionalTest.php
@@ -31,7 +31,7 @@ use Twig\Test\NodeTestCase;
 #[Group('legacy')]
 class ConditionalTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $expr1 = new ConstantExpression(1, 1);
         $expr2 = new ConstantExpression(2, 1);
diff --git a/tests/Node/Expression/ConstantTest.php b/tests/Node/Expression/ConstantTest.php
index 62fefddc4..8c68702dc 100644
--- a/tests/Node/Expression/ConstantTest.php
+++ b/tests/Node/Expression/ConstantTest.php
@@ -25,7 +25,7 @@ use Twig\Test\NodeTestCase;
 
 class ConstantTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $node = new ConstantExpression('foo', 1);
 
diff --git a/tests/Node/Expression/Filter/RawTest.php b/tests/Node/Expression/Filter/RawTest.php
index c254bf8c0..8e43b7823 100644
--- a/tests/Node/Expression/Filter/RawTest.php
+++ b/tests/Node/Expression/Filter/RawTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class RawTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $filter = new RawFilter($node = new ConstantExpression('foo', 12));
 
diff --git a/tests/Node/Expression/FilterTest.php b/tests/Node/Expression/FilterTest.php
index e77dd5bb8..af26a5cb4 100644
--- a/tests/Node/Expression/FilterTest.php
+++ b/tests/Node/Expression/FilterTest.php
@@ -33,7 +33,7 @@ use Twig\TwigFilter;
 
 class FilterTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $expr = new ConstantExpression('foo', 1);
         $filter = new TwigFilter($name = 'upper');
@@ -144,7 +144,7 @@ class FilterTest extends NodeTestCase
         return $tests;
     }
 
-    public function testCompileWithWrongNamedArgumentName()
+    public function testCompileWithWrongNamedArgumentName(): void
     {
         $date = new ConstantExpression(0, 1);
         $node = $this->createFilter($this->getEnvironment(), $date, 'date', [
@@ -159,7 +159,7 @@ class FilterTest extends NodeTestCase
         $compiler->compile($node);
     }
 
-    public function testCompileWithMissingNamedArgument()
+    public function testCompileWithMissingNamedArgument(): void
     {
         $value = new ConstantExpression(0, 1);
         $node = $this->createFilter($this->getEnvironment(), $value, 'replace', [
@@ -208,30 +208,30 @@ class FilterTest extends NodeTestCase
                 ];
             }
 
-            public function foo()
+            public function foo(): void
             {
             }
 
-            protected function foobar()
+            protected function foobar(): void
             {
             }
         };
     }
 }
 
-function twig_tests_filter_dummy()
+function twig_tests_filter_dummy(): void
 {
 }
 
-function twig_tests_filter_barbar($context, $string, $arg1 = null, $arg2 = null, array $args = [])
+function twig_tests_filter_barbar($context, $string, $arg1 = null, $arg2 = null, array $args = []): void
 {
 }
 
-function twig_tests_filter_sandbox(bool $isSandboxed, $string)
+function twig_tests_filter_sandbox(bool $isSandboxed, $string): void
 {
 }
 
-function twig_tests_filter_all(string $charset, Environment $env, array $context, bool $isSandboxed, $string)
+function twig_tests_filter_all(string $charset, Environment $env, array $context, bool $isSandboxed, $string): void
 {
 }
 
@@ -245,7 +245,7 @@ class ChildMagicCallStub extends ParentMagicCallStub
 
 class ParentMagicCallStub
 {
-    public static function identifier()
+    public static function identifier(): void
     {
         throw new \Exception('Identifier has not been defined.');
     }
diff --git a/tests/Node/Expression/FilterTestExtension.php b/tests/Node/Expression/FilterTestExtension.php
index 789f05c9e..7e442648d 100644
--- a/tests/Node/Expression/FilterTestExtension.php
+++ b/tests/Node/Expression/FilterTestExtension.php
@@ -33,11 +33,11 @@ class FilterTestExtension extends AbstractExtension
         ];
     }
 
-    public static function staticMethod()
+    public static function staticMethod(): void
     {
     }
 
-    public function objectMethod()
+    public function objectMethod(): void
     {
     }
 }
diff --git a/tests/Node/Expression/FunctionTest.php b/tests/Node/Expression/FunctionTest.php
index 7cecd72b3..8b2d29961 100644
--- a/tests/Node/Expression/FunctionTest.php
+++ b/tests/Node/Expression/FunctionTest.php
@@ -31,7 +31,7 @@ use Twig\TwigFunction;
 
 class FunctionTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $name = 'function';
         $args = new EmptyNode();
@@ -126,10 +126,10 @@ class FunctionTest extends NodeTestCase
     }
 }
 
-function twig_tests_function_dummy()
+function twig_tests_function_dummy(): void
 {
 }
 
-function twig_tests_function_barbar($arg1 = null, $arg2 = null, array $args = [])
+function twig_tests_function_barbar($arg1 = null, $arg2 = null, array $args = []): void
 {
 }
diff --git a/tests/Node/Expression/GetAttrTest.php b/tests/Node/Expression/GetAttrTest.php
index a4454f9fd..055645aa5 100644
--- a/tests/Node/Expression/GetAttrTest.php
+++ b/tests/Node/Expression/GetAttrTest.php
@@ -29,7 +29,7 @@ use Twig\Test\NodeTestCase;
 
 class GetAttrTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $expr = new ContextVariable('foo', 1);
         $attr = new ConstantExpression('bar', 1);
diff --git a/tests/Node/Expression/MacroReferenceTest.php b/tests/Node/Expression/MacroReferenceTest.php
index b823cf75b..e3b85c7b9 100644
--- a/tests/Node/Expression/MacroReferenceTest.php
+++ b/tests/Node/Expression/MacroReferenceTest.php
@@ -26,7 +26,7 @@ class MacroReferenceTest extends TestCase
      * @dataProvider provideInvalidMacroNames
      */
     #[DataProvider('provideInvalidMacroNames')]
-    public function testConstructorRejectsNonIdentifierName(string $name)
+    public function testConstructorRejectsNonIdentifierName(string $name): void
     {
         $this->expectException(\LogicException::class);
         $this->expectExceptionMessage(\sprintf('Macro name "%s" is not a valid PHP identifier.', $name));
@@ -44,7 +44,7 @@ class MacroReferenceTest extends TestCase
         yield 'contains NUL byte' => ["foo\x00bar"];
     }
 
-    public function testConstructorAcceptsAnExpressionAsName()
+    public function testConstructorAcceptsAnExpressionAsName(): void
     {
         $node = new MacroReferenceExpression(new TemplateVariable('foo', 1), new ContextVariable('name', 1), new ArrayExpression([], 1), 1);
 
@@ -52,7 +52,7 @@ class MacroReferenceTest extends TestCase
         $this->assertNull($node->getAttribute('name'));
     }
 
-    public function testDynamicNamePrefixesMacroAtRuntime()
+    public function testDynamicNamePrefixesMacroAtRuntime(): void
     {
         $env = new Environment(new ArrayLoader());
         $compiler = new \Twig\Compiler($env);
diff --git a/tests/Node/Expression/ParentTest.php b/tests/Node/Expression/ParentTest.php
index 94cbc2d22..7bcfb6c68 100644
--- a/tests/Node/Expression/ParentTest.php
+++ b/tests/Node/Expression/ParentTest.php
@@ -25,7 +25,7 @@ use Twig\Test\NodeTestCase;
 
 class ParentTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $node = new ParentExpression('foo', 1);
 
diff --git a/tests/Node/Expression/Ternary/ConditionalTernaryTest.php b/tests/Node/Expression/Ternary/ConditionalTernaryTest.php
index d8cc8da3d..3fe8cfea1 100644
--- a/tests/Node/Expression/Ternary/ConditionalTernaryTest.php
+++ b/tests/Node/Expression/Ternary/ConditionalTernaryTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class ConditionalTernaryTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $test = new ConstantExpression(1, 1);
         $left = new ConstantExpression(2, 1);
diff --git a/tests/Node/Expression/TestTest.php b/tests/Node/Expression/TestTest.php
index 6ffea5541..eae140dfb 100644
--- a/tests/Node/Expression/TestTest.php
+++ b/tests/Node/Expression/TestTest.php
@@ -32,7 +32,7 @@ use Twig\TwigTest;
 
 class TestTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $expr = new ConstantExpression('foo', 1);
         $name = 'test_name';
@@ -95,6 +95,6 @@ class TestTest extends NodeTestCase
     }
 }
 
-function twig_tests_test_barbar($string, $arg1 = null, $arg2 = null, array $args = [])
+function twig_tests_test_barbar($string, $arg1 = null, $arg2 = null, array $args = []): void
 {
 }
diff --git a/tests/Node/Expression/Unary/NegTest.php b/tests/Node/Expression/Unary/NegTest.php
index 06089e5fd..405f291cf 100644
--- a/tests/Node/Expression/Unary/NegTest.php
+++ b/tests/Node/Expression/Unary/NegTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class NegTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $expr = new ConstantExpression(1, 1);
         $node = new NegUnary($expr, 1);
diff --git a/tests/Node/Expression/Unary/NotTest.php b/tests/Node/Expression/Unary/NotTest.php
index de90a15c8..159c8ba84 100644
--- a/tests/Node/Expression/Unary/NotTest.php
+++ b/tests/Node/Expression/Unary/NotTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class NotTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $expr = new ConstantExpression(1, 1);
         $node = new NotUnary($expr, 1);
diff --git a/tests/Node/Expression/Unary/PosTest.php b/tests/Node/Expression/Unary/PosTest.php
index 46ba9774a..486b7ff6f 100644
--- a/tests/Node/Expression/Unary/PosTest.php
+++ b/tests/Node/Expression/Unary/PosTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class PosTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $expr = new ConstantExpression(1, 1);
         $node = new PosUnary($expr, 1);
diff --git a/tests/Node/Expression/Variable/AssignContextVariableTest.php b/tests/Node/Expression/Variable/AssignContextVariableTest.php
index 84deaa80b..fd1b4fab6 100644
--- a/tests/Node/Expression/Variable/AssignContextVariableTest.php
+++ b/tests/Node/Expression/Variable/AssignContextVariableTest.php
@@ -25,7 +25,7 @@ use Twig\Test\NodeTestCase;
 
 class AssignContextVariableTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $node = new AssignContextVariable('foo', 1);
 
diff --git a/tests/Node/Expression/Variable/ContextVariableTest.php b/tests/Node/Expression/Variable/ContextVariableTest.php
index c10aaf2a9..d0a26e247 100644
--- a/tests/Node/Expression/Variable/ContextVariableTest.php
+++ b/tests/Node/Expression/Variable/ContextVariableTest.php
@@ -27,7 +27,7 @@ use Twig\Test\NodeTestCase;
 
 class ContextVariableTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $node = new ContextVariable('foo', 1);
 
diff --git a/tests/Node/ForTest.php b/tests/Node/ForTest.php
index 9a642073c..b9203be41 100644
--- a/tests/Node/ForTest.php
+++ b/tests/Node/ForTest.php
@@ -30,7 +30,7 @@ use Twig\Test\NodeTestCase;
 
 class ForTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $keyTarget = new AssignContextVariable('key', 1);
         $valueTarget = new AssignContextVariable('item', 1);
diff --git a/tests/Node/IfTest.php b/tests/Node/IfTest.php
index 7ce06e817..ab9d9efbe 100644
--- a/tests/Node/IfTest.php
+++ b/tests/Node/IfTest.php
@@ -29,7 +29,7 @@ use Twig\Test\NodeTestCase;
 
 class IfTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $t = new Nodes([
             new ConstantExpression(true, 1),
diff --git a/tests/Node/ImportTest.php b/tests/Node/ImportTest.php
index 314cf0622..cb96ba4da 100644
--- a/tests/Node/ImportTest.php
+++ b/tests/Node/ImportTest.php
@@ -28,7 +28,7 @@ use Twig\Test\NodeTestCase;
 
 class ImportTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $macro = new ConstantExpression('foo.twig', 1);
         $node = new ImportNode($macro, new AssignTemplateVariable(new TemplateVariable('macro', 1), true), 1);
diff --git a/tests/Node/IncludeTest.php b/tests/Node/IncludeTest.php
index 7bf807184..7d3d2bf90 100644
--- a/tests/Node/IncludeTest.php
+++ b/tests/Node/IncludeTest.php
@@ -28,7 +28,7 @@ use Twig\Test\NodeTestCase;
 
 class IncludeTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $expr = new ConstantExpression('foo.twig', 1);
         $node = new IncludeNode($expr, null, false, false, 1);
diff --git a/tests/Node/MacroTest.php b/tests/Node/MacroTest.php
index 4f5b4e02b..9af745bdd 100644
--- a/tests/Node/MacroTest.php
+++ b/tests/Node/MacroTest.php
@@ -33,7 +33,7 @@ use Twig\Test\NodeTestCase;
 
 class MacroTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $body = new BodyNode([new TextNode('foo', 1)]);
         $arguments = new ArrayExpression([new ContextVariable('foo', 1), new ConstantExpression(null, 1)], 1);
diff --git a/tests/Node/ModuleTest.php b/tests/Node/ModuleTest.php
index 9b8331aea..7b8c9e07d 100644
--- a/tests/Node/ModuleTest.php
+++ b/tests/Node/ModuleTest.php
@@ -40,7 +40,7 @@ use Twig\Test\NodeTestCase;
 
 class ModuleTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $body = new BodyNode([new TextNode('foo', 1)]);
         $parent = new ConstantExpression('layout.twig', 1);
@@ -57,7 +57,7 @@ class ModuleTest extends NodeTestCase
         $this->assertEquals($source->getName(), $node->getTemplateName());
     }
 
-    public function testUseTagTemplateNameDoesNotInjectPhpInCompiledOutput()
+    public function testUseTagTemplateNameDoesNotInjectPhpInCompiledOutput(): void
     {
         $evilName = "evil' . print('BAD-EOL') . '.twig";
         $loader = new ArrayLoader([
diff --git a/tests/Node/NodeTest.php b/tests/Node/NodeTest.php
index 0dc0df934..b5a744137 100644
--- a/tests/Node/NodeTest.php
+++ b/tests/Node/NodeTest.php
@@ -33,7 +33,7 @@ class NodeTest extends TestCase
 {
     use ExpectDeprecationTrait;
 
-    public function testToString()
+    public function testToString(): void
     {
         // callable is not a supported type for a Node attribute, but Drupal uses some apparently
         $node = new NodeForTest([], ['value' => static function () { return '1'; }], 1);
@@ -46,7 +46,7 @@ EOF, (string) $node
         );
     }
 
-    public function testToStringWithTwigCallables()
+    public function testToStringWithTwigCallables(): void
     {
         $node = new NodeForTest([], [
             'function' => new TwigFunction('a_function'),
@@ -63,7 +63,7 @@ Twig\Tests\Node\NodeForTest
 EOF, (string) $node);
     }
 
-    public function testToStringWithTag()
+    public function testToStringWithTag(): void
     {
         $node = new NodeForTest();
         $node->setNodeTag('tag');
@@ -74,7 +74,7 @@ Twig\Tests\Node\NodeForTest
 EOF, (string) $node);
     }
 
-    public function testAttributeDeprecationIgnore()
+    public function testAttributeDeprecationIgnore(): void
     {
         $node = new NodeForTest([], ['foo' => false]);
         $node->deprecateAttribute('foo', new NameDeprecation('foo/bar', '2.0', 'bar'));
@@ -86,7 +86,7 @@ EOF, (string) $node);
      * @group legacy
      */
     #[Group('legacy')]
-    public function testAttributeDeprecationWithoutAlternative()
+    public function testAttributeDeprecationWithoutAlternative(): void
     {
         $node = new NodeForTest([], ['foo' => false]);
         $node->deprecateAttribute('foo', new NameDeprecation('foo/bar', '2.0'));
@@ -99,7 +99,7 @@ EOF, (string) $node);
      * @group legacy
      */
     #[Group('legacy')]
-    public function testAttributeDeprecationWithAlternative()
+    public function testAttributeDeprecationWithAlternative(): void
     {
         $node = new NodeForTest([], ['foo' => false]);
         $node->deprecateAttribute('foo', new NameDeprecation('foo/bar', '2.0', 'bar'));
@@ -108,7 +108,7 @@ EOF, (string) $node);
         $this->assertFalse($node->getAttribute('foo'));
     }
 
-    public function testNodeDeprecationIgnore()
+    public function testNodeDeprecationIgnore(): void
     {
         $node = new NodeForTest(['foo' => $foo = new NodeForTest()]);
         $node->deprecateNode('foo', new NameDeprecation('foo/bar', '2.0'));
@@ -120,7 +120,7 @@ EOF, (string) $node);
      * @group legacy
      */
     #[Group('legacy')]
-    public function testNodeDeprecationWithoutAlternative()
+    public function testNodeDeprecationWithoutAlternative(): void
     {
         $node = new NodeForTest(['foo' => $foo = new NodeForTest()]);
         $node->deprecateNode('foo', new NameDeprecation('foo/bar', '2.0'));
@@ -133,7 +133,7 @@ EOF, (string) $node);
      * @group legacy
      */
     #[Group('legacy')]
-    public function testNodeAttributeDeprecationWithAlternative()
+    public function testNodeAttributeDeprecationWithAlternative(): void
     {
         $node = new NodeForTest(['foo' => $foo = new NodeForTest()]);
         $node->deprecateNode('foo', new NameDeprecation('foo/bar', '2.0', 'bar'));
diff --git a/tests/Node/PrintTest.php b/tests/Node/PrintTest.php
index 7d57b5b21..c4d3079b2 100644
--- a/tests/Node/PrintTest.php
+++ b/tests/Node/PrintTest.php
@@ -30,7 +30,7 @@ use Twig\Test\NodeTestCase;
 
 class PrintTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $expr = new ConstantExpression('foo', 1);
         $node = new PrintNode($expr, 1);
diff --git a/tests/Node/SandboxTest.php b/tests/Node/SandboxTest.php
index c8df0ad8d..a5a5985db 100644
--- a/tests/Node/SandboxTest.php
+++ b/tests/Node/SandboxTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class SandboxTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $body = new TextNode('foo', 1);
         $node = new SandboxNode($body, 1);
diff --git a/tests/Node/SetTest.php b/tests/Node/SetTest.php
index 6cffe37b9..4cfd85aca 100644
--- a/tests/Node/SetTest.php
+++ b/tests/Node/SetTest.php
@@ -33,7 +33,7 @@ use Twig\Test\NodeTestCase;
 
 class SetTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $names = new Nodes([new AssignContextVariable('foo', 1)], 1);
         $values = new Nodes([new ConstantExpression('foo', 1)], 1);
diff --git a/tests/Node/TextTest.php b/tests/Node/TextTest.php
index 748ded6e4..9cd1bb85f 100644
--- a/tests/Node/TextTest.php
+++ b/tests/Node/TextTest.php
@@ -26,7 +26,7 @@ use Twig\Test\NodeTestCase;
 
 class TextTest extends NodeTestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $node = new TextNode('foo', 1);
 
@@ -45,7 +45,7 @@ class TextTest extends NodeTestCase
      * @dataProvider getIsBlankData
      */
     #[DataProvider('getIsBlankData')]
-    public function testIsBlank($blank)
+    public function testIsBlank($blank): void
     {
         $this->assertTrue((new TextNode($blank, 1))->isBlank());
         $this->assertTrue((new TextNode(\chr(0xEF).\chr(0xBB).\chr(0xBF).$blank, 1))->isBlank());
diff --git a/tests/Node/TypesTest.php b/tests/Node/TypesTest.php
index 0bb1ef044..e9ae845e9 100644
--- a/tests/Node/TypesTest.php
+++ b/tests/Node/TypesTest.php
@@ -31,7 +31,7 @@ class TypesTest extends NodeTestCase
         ];
     }
 
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $types = self::getValidMapping();
         $node = new TypesNode($types, 1);
diff --git a/tests/NodeVisitor/CorrectnessTest.php b/tests/NodeVisitor/CorrectnessTest.php
index 75b1b7f3c..ab2a9a418 100644
--- a/tests/NodeVisitor/CorrectnessTest.php
+++ b/tests/NodeVisitor/CorrectnessTest.php
@@ -36,7 +36,7 @@ class CorrectnessTest extends TestCase
      * @dataProvider getFilterBodyNodesData
      */
     #[DataProvider('getFilterBodyNodesData')]
-    public function testFilterBodyNodes($input, $expected)
+    public function testFilterBodyNodes($input, $expected): void
     {
         $this->assertEquals($expected, $this->traverse($input, $expected));
     }
@@ -59,7 +59,7 @@ class CorrectnessTest extends TestCase
      * @dataProvider getFilterBodyNodesDataThrowsException
      */
     #[DataProvider('getFilterBodyNodesDataThrowsException')]
-    public function testFilterBodyNodesThrowsException($input)
+    public function testFilterBodyNodesThrowsException($input): void
     {
         $this->expectException(SyntaxError::class);
         $this->traverse($input, new EmptyNode());
@@ -79,7 +79,7 @@ class CorrectnessTest extends TestCase
      * @dataProvider getFilterBodyNodesWithBOMData
      */
     #[DataProvider('getFilterBodyNodesWithBOMData')]
-    public function testFilterBodyNodesWithBOM($emptyText)
+    public function testFilterBodyNodesWithBOM($emptyText): void
     {
         $input = new TextNode(\chr(0xEF).\chr(0xBB).\chr(0xBF).$emptyText, 1);
 
diff --git a/tests/NodeVisitor/OptimizerTest.php b/tests/NodeVisitor/OptimizerTest.php
index 0cebea8ef..5a7799049 100644
--- a/tests/NodeVisitor/OptimizerTest.php
+++ b/tests/NodeVisitor/OptimizerTest.php
@@ -34,14 +34,14 @@ use Twig\Source;
 
 class OptimizerTest extends TestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $this->expectNotToPerformAssertions();
 
         new OptimizerNodeVisitor(OptimizerNodeVisitor::OPTIMIZE_FOR);
     }
 
-    public function testRenderBlockOptimizer()
+    public function testRenderBlockOptimizer(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
 
@@ -53,7 +53,7 @@ class OptimizerTest extends TestCase
         $this->assertTrue($node->getAttribute('output'));
     }
 
-    public function testRenderParentBlockOptimizer()
+    public function testRenderParentBlockOptimizer(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
 
@@ -65,7 +65,7 @@ class OptimizerTest extends TestCase
         $this->assertTrue($node->getAttribute('output'));
     }
 
-    public function testForVarOptimizer()
+    public function testForVarOptimizer(): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false, 'autoescape' => false]);
 
@@ -77,7 +77,7 @@ class OptimizerTest extends TestCase
         }
     }
 
-    public function checkForVarConfiguration(Node $node, $target)
+    public function checkForVarConfiguration(Node $node, $target): void
     {
         foreach ($node as $n) {
             if (NameExpression::class === $n::class && $target === $n->getAttribute('name')) {
@@ -92,7 +92,7 @@ class OptimizerTest extends TestCase
      * @dataProvider getTestsForForLoopOptimizer
      */
     #[DataProvider('getTestsForForLoopOptimizer')]
-    public function testForLoopOptimizer($template, $expected)
+    public function testForLoopOptimizer($template, $expected): void
     {
         $env = new Environment(new ArrayLoader(), ['cache' => false]);
 
diff --git a/tests/NodeVisitor/SandboxTest.php b/tests/NodeVisitor/SandboxTest.php
index 8165464ad..bda8fdb18 100644
--- a/tests/NodeVisitor/SandboxTest.php
+++ b/tests/NodeVisitor/SandboxTest.php
@@ -38,7 +38,7 @@ use Twig\Source;
 
 class SandboxTest extends TestCase
 {
-    public function testGeneratorExpression()
+    public function testGeneratorExpression(): void
     {
         $env = new Environment(new ArrayLoader());
         $expr = new ContextVariable('foo', 1);
@@ -51,7 +51,7 @@ class SandboxTest extends TestCase
         $this->assertSame("// line 1\nyield from (\$context[\"foo\"] ?? null);\n", $env->compile($node->getNode('body')));
     }
 
-    public function testCustomNodeImplementingCoercesChildrenToStringInterfaceIsWrapped()
+    public function testCustomNodeImplementingCoercesChildrenToStringInterfaceIsWrapped(): void
     {
         $env = new Environment(new ArrayLoader());
         $custom = new CustomCoercingExpression(new ContextVariable('foo', 1), new ContextVariable('bar', 1), 1);
@@ -66,7 +66,7 @@ class SandboxTest extends TestCase
         $this->assertInstanceOf(CheckToStringNode::class, $custom->getNode('right'));
     }
 
-    public function testCustomNonExpressionNodeImplementingCoercesChildrenToStringInterfaceIsWrapped()
+    public function testCustomNonExpressionNodeImplementingCoercesChildrenToStringInterfaceIsWrapped(): void
     {
         $env = new Environment(new ArrayLoader());
         $custom = new CustomCoercingNode(['expr' => new ContextVariable('foo', 1)], [], 1);
@@ -78,7 +78,7 @@ class SandboxTest extends TestCase
         $this->assertInstanceOf(CheckToStringNode::class, $custom->getNode('expr'));
     }
 
-    public function testSelfIsNeverWrapped()
+    public function testSelfIsNeverWrapped(): void
     {
         $env = new Environment(new ArrayLoader());
         $self = new ContextVariable('_self', 1);
diff --git a/tests/ParserTest.php b/tests/ParserTest.php
index 703f82401..6cc5ddaed 100644
--- a/tests/ParserTest.php
+++ b/tests/ParserTest.php
@@ -37,7 +37,7 @@ use Twig\TokenStream;
 
 class ParserTest extends TestCase
 {
-    public function testUnknownTag()
+    public function testUnknownTag(): void
     {
         $stream = new TokenStream([
             new Token(Token::BLOCK_START_TYPE, '', 1),
@@ -53,7 +53,7 @@ class ParserTest extends TestCase
         $parser->parse($stream);
     }
 
-    public function testUnknownTagWithoutSuggestions()
+    public function testUnknownTagWithoutSuggestions(): void
     {
         $stream = new TokenStream([
             new Token(Token::BLOCK_START_TYPE, '', 1),
@@ -69,7 +69,7 @@ class ParserTest extends TestCase
         $parser->parse($stream);
     }
 
-    public function testParseIsReentrant()
+    public function testParseIsReentrant(): void
     {
         $twig = new Environment(new ArrayLoader(), [
             'autoescape' => false,
@@ -93,7 +93,7 @@ class ParserTest extends TestCase
         $this->assertNull($p->getValue($parser));
     }
 
-    public function testGetVarName()
+    public function testGetVarName(): void
     {
         $twig = new Environment(new ArrayLoader(), [
             'autoescape' => false,
@@ -113,7 +113,7 @@ EOF, 'index')));
         $this->addToAssertionCount(1);
     }
 
-    public function testImplicitMacroArgumentDefaultValues()
+    public function testImplicitMacroArgumentDefaultValues(): void
     {
         $template = '{% macro marco (po, lo = true) %}{% endmacro %}';
         $lexer = new Lexer(new Environment(new ArrayLoader()));
@@ -147,7 +147,7 @@ EOF, 'index')));
         $this->assertSame(2, $embeds->getNode(1)->getAttribute('index'));
     }
 
-    public function testBodyForChildTemplates()
+    public function testBodyForChildTemplates(): void
     {
         $twig = new Environment(new ArrayLoader());
         $node = $twig->parse($twig->tokenize(new Source(<<<EOF
@@ -171,7 +171,7 @@ EOF, 'index')));
         $this->assertSame('set', $body->getNode('4')->getNodeTag());
     }
 
-    public function testCleanupBodyForChildTemplatesWithASingleNodeBody()
+    public function testCleanupBodyForChildTemplatesWithASingleNodeBody(): void
     {
         $twig = new Environment(new ArrayLoader());
         $twig->addTokenParser(new ParentSettingTokenParser());
@@ -182,7 +182,7 @@ EOF, 'index')));
         $this->assertInstanceOf(EmptyNode::class, $body);
     }
 
-    public function testBodyForParentTemplates()
+    public function testBodyForParentTemplates(): void
     {
         $twig = new Environment(new ArrayLoader());
         $node = $twig->parse($twig->tokenize(new Source(<<<EOF
diff --git a/tests/Profiler/Dumper/BlackfireTest.php b/tests/Profiler/Dumper/BlackfireTest.php
index eb93bd576..dc9697f2d 100644
--- a/tests/Profiler/Dumper/BlackfireTest.php
+++ b/tests/Profiler/Dumper/BlackfireTest.php
@@ -24,7 +24,7 @@ use Twig\Profiler\Dumper\BlackfireDumper;
 
 class BlackfireTest extends ProfilerTestCase
 {
-    public function testDump()
+    public function testDump(): void
     {
         $dumper = new BlackfireDumper();
 
diff --git a/tests/Profiler/Dumper/HtmlTest.php b/tests/Profiler/Dumper/HtmlTest.php
index 75ddb791d..d0de2e6c2 100644
--- a/tests/Profiler/Dumper/HtmlTest.php
+++ b/tests/Profiler/Dumper/HtmlTest.php
@@ -25,7 +25,7 @@ use Twig\Profiler\Profile;
 
 class HtmlTest extends ProfilerTestCase
 {
-    public function testDump()
+    public function testDump(): void
     {
         $dumper = new HtmlDumper();
         $this->assertStringMatchesFormat(<<<EOF
@@ -41,7 +41,7 @@ class HtmlTest extends ProfilerTestCase
 EOF, $dumper->dump($this->getProfile()));
     }
 
-    public function testDumpEscapesTemplateAndProfileNames()
+    public function testDumpEscapesTemplateAndProfileNames(): void
     {
         $root = new Profile('main');
         $child = new Profile('<img src=x onerror=alert(1)>', Profile::TEMPLATE);
@@ -60,7 +60,7 @@ EOF, $dumper->dump($this->getProfile()));
         $this->assertStringContainsString('&lt;img src=x onerror=alert(3)&gt;', $output);
     }
 
-    public function testDumpEscapesRootProfileName()
+    public function testDumpEscapesRootProfileName(): void
     {
         $root = new Profile('template-name', Profile::ROOT, '<img src=x onerror=alert(1)>');
 
diff --git a/tests/Profiler/Dumper/TextTest.php b/tests/Profiler/Dumper/TextTest.php
index 7d5e718b7..5fc4d2eca 100644
--- a/tests/Profiler/Dumper/TextTest.php
+++ b/tests/Profiler/Dumper/TextTest.php
@@ -24,7 +24,7 @@ use Twig\Profiler\Dumper\TextDumper;
 
 class TextTest extends ProfilerTestCase
 {
-    public function testDump()
+    public function testDump(): void
     {
         $dumper = new TextDumper();
         $this->assertStringMatchesFormat(<<<EOF
diff --git a/tests/Profiler/ProfileTest.php b/tests/Profiler/ProfileTest.php
index 5a5e8871f..f147214f6 100644
--- a/tests/Profiler/ProfileTest.php
+++ b/tests/Profiler/ProfileTest.php
@@ -25,7 +25,7 @@ use Twig\Profiler\Profile;
 
 class ProfileTest extends TestCase
 {
-    public function testConstructor()
+    public function testConstructor(): void
     {
         $profile = new Profile('template', 'type', 'name');
 
@@ -34,7 +34,7 @@ class ProfileTest extends TestCase
         $this->assertEquals('name', $profile->getName());
     }
 
-    public function testIsRoot()
+    public function testIsRoot(): void
     {
         $profile = new Profile('template', Profile::ROOT);
         $this->assertTrue($profile->isRoot());
@@ -43,7 +43,7 @@ class ProfileTest extends TestCase
         $this->assertFalse($profile->isRoot());
     }
 
-    public function testIsTemplate()
+    public function testIsTemplate(): void
     {
         $profile = new Profile('template', Profile::TEMPLATE);
         $this->assertTrue($profile->isTemplate());
@@ -52,7 +52,7 @@ class ProfileTest extends TestCase
         $this->assertFalse($profile->isTemplate());
     }
 
-    public function testIsBlock()
+    public function testIsBlock(): void
     {
         $profile = new Profile('template', Profile::BLOCK);
         $this->assertTrue($profile->isBlock());
@@ -61,7 +61,7 @@ class ProfileTest extends TestCase
         $this->assertFalse($profile->isBlock());
     }
 
-    public function testIsMacro()
+    public function testIsMacro(): void
     {
         $profile = new Profile('template', Profile::MACRO);
         $this->assertTrue($profile->isMacro());
@@ -70,7 +70,7 @@ class ProfileTest extends TestCase
         $this->assertFalse($profile->isMacro());
     }
 
-    public function testGetAddProfile()
+    public function testGetAddProfile(): void
     {
         $profile = new Profile();
         $profile->addProfile($a = new Profile());
@@ -80,7 +80,7 @@ class ProfileTest extends TestCase
         $this->assertSame([$a, $b], iterator_to_array($profile));
     }
 
-    public function testGetDuration()
+    public function testGetDuration(): void
     {
         $profile = new Profile();
         usleep(1);
@@ -89,7 +89,7 @@ class ProfileTest extends TestCase
         $this->assertTrue($profile->getDuration() > 0, \sprintf('Expected duration > 0, got: %f', $profile->getDuration()));
     }
 
-    public function testTimeAccessors()
+    public function testTimeAccessors(): void
     {
         $current = microtime(true);
         $profile = new Profile();
@@ -98,7 +98,7 @@ class ProfileTest extends TestCase
         $this->assertSame(0.0, $profile->getEndTime());
     }
 
-    public function testSerialize()
+    public function testSerialize(): void
     {
         $profile = new Profile('template', 'type', 'name');
         $profile1 = new Profile('template1', 'type1', 'name1');
@@ -121,7 +121,7 @@ class ProfileTest extends TestCase
         $this->assertEquals($profile1->getName(), $profile3->getName());
     }
 
-    public function testUnserializeDoesNotInstantiateArbitraryClasses()
+    public function testUnserializeDoesNotInstantiateArbitraryClasses(): void
     {
         $payload = serialize([
             'template',
@@ -138,7 +138,7 @@ class ProfileTest extends TestCase
         $this->assertFalse(ProfileTestProbe::$wakeupCalled, 'Magic unserialize methods must not be called on arbitrary classes');
     }
 
-    public function testReset()
+    public function testReset(): void
     {
         $profile = new Profile();
         usleep(1);
diff --git a/tests/Resources/LegacyCoreTest.php b/tests/Resources/LegacyCoreTest.php
index d6dedab4e..11ce2caef 100644
--- a/tests/Resources/LegacyCoreTest.php
+++ b/tests/Resources/LegacyCoreTest.php
@@ -35,7 +35,7 @@ require_once __DIR__.'/../../src/Resources/core.php';
 #[Group('legacy')]
 class LegacyCoreTest extends TestCase
 {
-    public function testTwigSortFilterEnforcesGlobalSandbox()
+    public function testTwigSortFilterEnforcesGlobalSandbox(): void
     {
         $env = $this->createSandboxedEnvironment(true);
         $template = new LegacyCoreTestTemplate($env, 'index.twig');
@@ -46,7 +46,7 @@ class LegacyCoreTest extends TestCase
         $template->callLegacySort(['b', 'a'], 'strnatcasecmp');
     }
 
-    public function testTwigSortFilterRecoversSourceForSourcePolicy()
+    public function testTwigSortFilterRecoversSourceForSourcePolicy(): void
     {
         $env = $this->createSandboxedEnvironment(false, new class implements SourcePolicyInterface {
             public function enableSandbox(Source $source): bool
@@ -67,7 +67,7 @@ class LegacyCoreTest extends TestCase
         $sandboxedTemplate->callLegacySort(['b', 'a'], 'strnatcasecmp');
     }
 
-    public function testTwigArrayFilterRecoversSourceForSourcePolicy()
+    public function testTwigArrayFilterRecoversSourceForSourcePolicy(): void
     {
         $env = $this->createSandboxedEnvironment(false, new class implements SourcePolicyInterface {
             public function enableSandbox(Source $source): bool
@@ -83,7 +83,7 @@ class LegacyCoreTest extends TestCase
         iterator_to_array($template->callLegacyArrayFilter(['a', 'b'], 'is_string'));
     }
 
-    public function testTwigArrayMapRecoversSourceForSourcePolicy()
+    public function testTwigArrayMapRecoversSourceForSourcePolicy(): void
     {
         $env = $this->createSandboxedEnvironment(false, new class implements SourcePolicyInterface {
             public function enableSandbox(Source $source): bool
@@ -99,7 +99,7 @@ class LegacyCoreTest extends TestCase
         $template->callLegacyArrayMap(['a', 'b'], 'strtoupper');
     }
 
-    public function testTwigArrayColumnEnforcesSandbox()
+    public function testTwigArrayColumnEnforcesSandbox(): void
     {
         $env = $this->createSandboxedEnvironment(true);
         $template = new LegacyCoreTestTemplate($env, 'index.twig');
@@ -108,7 +108,7 @@ class LegacyCoreTest extends TestCase
         $template->callLegacyArrayColumn([new LegacyColumnObject()], 'bar');
     }
 
-    public function testTwigArrayReduceRecoversSourceForSourcePolicy()
+    public function testTwigArrayReduceRecoversSourceForSourcePolicy(): void
     {
         $env = $this->createSandboxedEnvironment(false, new class implements SourcePolicyInterface {
             public function enableSandbox(Source $source): bool
@@ -124,7 +124,7 @@ class LegacyCoreTest extends TestCase
         $template->callLegacyArrayReduce([1, 2], 'intval');
     }
 
-    public function testTwigArraySomeEnforcesGlobalSandbox()
+    public function testTwigArraySomeEnforcesGlobalSandbox(): void
     {
         $env = $this->createSandboxedEnvironment(true);
         $template = new LegacyCoreTestTemplate($env, 'index.twig');
@@ -134,7 +134,7 @@ class LegacyCoreTest extends TestCase
         $template->callLegacyArraySome(['a', 'b'], 'is_string');
     }
 
-    public function testTwigArraySomeRecoversSourceForSourcePolicy()
+    public function testTwigArraySomeRecoversSourceForSourcePolicy(): void
     {
         $env = $this->createSandboxedEnvironment(false, new class implements SourcePolicyInterface {
             public function enableSandbox(Source $source): bool
@@ -150,7 +150,7 @@ class LegacyCoreTest extends TestCase
         $template->callLegacyArraySome(['a', 'b'], 'is_string');
     }
 
-    public function testTwigArrayEveryEnforcesGlobalSandbox()
+    public function testTwigArrayEveryEnforcesGlobalSandbox(): void
     {
         $env = $this->createSandboxedEnvironment(true);
         $template = new LegacyCoreTestTemplate($env, 'index.twig');
@@ -160,7 +160,7 @@ class LegacyCoreTest extends TestCase
         $template->callLegacyArrayEvery(['a', 'b'], 'is_string');
     }
 
-    public function testTwigArrayEveryRecoversSourceForSourcePolicy()
+    public function testTwigArrayEveryRecoversSourceForSourcePolicy(): void
     {
         $env = $this->createSandboxedEnvironment(false, new class implements SourcePolicyInterface {
             public function enableSandbox(Source $source): bool
@@ -176,7 +176,7 @@ class LegacyCoreTest extends TestCase
         $template->callLegacyArrayEvery(['a', 'b'], 'is_string');
     }
 
-    public function testTwigCheckArrowInSandboxEnforcesGlobalSandbox()
+    public function testTwigCheckArrowInSandboxEnforcesGlobalSandbox(): void
     {
         $env = $this->createSandboxedEnvironment(true);
         $template = new LegacyCoreTestTemplate($env, 'index.twig');
@@ -186,7 +186,7 @@ class LegacyCoreTest extends TestCase
         $template->callLegacyCheckArrowInSandbox('strlen', 'test', 'filter');
     }
 
-    public function testTwigCheckArrowInSandboxRecoversSourceForSourcePolicy()
+    public function testTwigCheckArrowInSandboxRecoversSourceForSourcePolicy(): void
     {
         $env = $this->createSandboxedEnvironment(false, new class implements SourcePolicyInterface {
             public function enableSandbox(Source $source): bool
@@ -202,7 +202,7 @@ class LegacyCoreTest extends TestCase
         $template->callLegacyCheckArrowInSandbox('strlen', 'test', 'filter');
     }
 
-    public function testTwigCheckArrowInSandboxIsNoopWhenNotSandboxed()
+    public function testTwigCheckArrowInSandboxIsNoopWhenNotSandboxed(): void
     {
         $env = $this->createSandboxedEnvironment(false);
         $template = new LegacyCoreTestTemplate($env, 'index.twig');
@@ -262,7 +262,7 @@ class LegacyCoreTestTemplate extends Template
         return twig_array_every($this->env, $array, $arrow);
     }
 
-    public function callLegacyCheckArrowInSandbox($arrow, $thing, $type)
+    public function callLegacyCheckArrowInSandbox($arrow, $thing, $type): void
     {
         twig_check_arrow_in_sandbox($this->env, $arrow, $thing, $type);
     }
diff --git a/tests/Runtime/EscaperRuntimeTest.php b/tests/Runtime/EscaperRuntimeTest.php
index 5c4e3e8b5..dbfe4abfa 100644
--- a/tests/Runtime/EscaperRuntimeTest.php
+++ b/tests/Runtime/EscaperRuntimeTest.php
@@ -166,35 +166,35 @@ class EscaperRuntimeTest extends TestCase
         ' ' => '\\20 ',
     ];
 
-    public function testHtmlEscapingConvertsSpecialChars()
+    public function testHtmlEscapingConvertsSpecialChars(): void
     {
         foreach ($this->htmlSpecialChars as $key => $value) {
             $this->assertEquals($value, (new EscaperRuntime())->escape($key, 'html'), 'Failed to escape: '.$key);
         }
     }
 
-    public function testHtmlAttributeEscapingConvertsSpecialChars()
+    public function testHtmlAttributeEscapingConvertsSpecialChars(): void
     {
         foreach ($this->htmlAttrSpecialChars as $key => $value) {
             $this->assertEquals($value, (new EscaperRuntime())->escape($key, 'html_attr'), 'Failed to escape: '.$key);
         }
     }
 
-    public function testHtmlAttributeRelaxedEscapingConvertsSpecialChars()
+    public function testHtmlAttributeRelaxedEscapingConvertsSpecialChars(): void
     {
         foreach ($this->htmlAttrSpecialChars as $key => $value) {
             $this->assertEquals($value, (new EscaperRuntime())->escape($key, 'html_attr_relaxed'), 'Failed to escape: '.$key);
         }
     }
 
-    public function testJavascriptEscapingConvertsSpecialChars()
+    public function testJavascriptEscapingConvertsSpecialChars(): void
     {
         foreach ($this->jsSpecialChars as $key => $value) {
             $this->assertEquals($value, (new EscaperRuntime())->escape($key, 'js'), 'Failed to escape: '.$key);
         }
     }
 
-    public function testJavascriptEscapingConvertsSpecialCharsWithInternalEncoding()
+    public function testJavascriptEscapingConvertsSpecialCharsWithInternalEncoding(): void
     {
         $previousInternalEncoding = mb_internal_encoding();
         try {
@@ -209,34 +209,34 @@ class EscaperRuntimeTest extends TestCase
         }
     }
 
-    public function testJavascriptEscapingReturnsStringIfZeroLength()
+    public function testJavascriptEscapingReturnsStringIfZeroLength(): void
     {
         $this->assertEquals('', (new EscaperRuntime())->escape('', 'js'));
     }
 
-    public function testJavascriptEscapingReturnsStringIfContainsOnlyDigits()
+    public function testJavascriptEscapingReturnsStringIfContainsOnlyDigits(): void
     {
         $this->assertEquals('123', (new EscaperRuntime())->escape('123', 'js'));
     }
 
-    public function testCssEscapingConvertsSpecialChars()
+    public function testCssEscapingConvertsSpecialChars(): void
     {
         foreach ($this->cssSpecialChars as $key => $value) {
             $this->assertEquals($value, (new EscaperRuntime())->escape($key, 'css'), 'Failed to escape: '.$key);
         }
     }
 
-    public function testCssEscapingReturnsStringIfZeroLength()
+    public function testCssEscapingReturnsStringIfZeroLength(): void
     {
         $this->assertEquals('', (new EscaperRuntime())->escape('', 'css'));
     }
 
-    public function testCssEscapingReturnsStringIfContainsOnlyDigits()
+    public function testCssEscapingReturnsStringIfContainsOnlyDigits(): void
     {
         $this->assertEquals('123', (new EscaperRuntime())->escape('123', 'css'));
     }
 
-    public function testUrlEscapingConvertsSpecialChars()
+    public function testUrlEscapingConvertsSpecialChars(): void
     {
         foreach ($this->urlSpecialChars as $key => $value) {
             $this->assertEquals($value, (new EscaperRuntime())->escape($key, 'url'), 'Failed to escape: '.$key);
@@ -251,7 +251,7 @@ class EscaperRuntimeTest extends TestCase
      * Only testing the first few 2 ranges on this prot. function as that's all these
      * other range tests require.
      */
-    public function testUnicodeCodepointConversionToUtf8()
+    public function testUnicodeCodepointConversionToUtf8(): void
     {
         $expected = ' ~ޙ';
         $codepoints = [0x20, 0x7E, 0x799];
@@ -292,7 +292,7 @@ class EscaperRuntimeTest extends TestCase
         throw new \Exception('Codepoint requested outside of Unicode range.');
     }
 
-    public function testJavascriptEscapingEscapesOwaspRecommendedRanges()
+    public function testJavascriptEscapingEscapesOwaspRecommendedRanges(): void
     {
         $immune = [',', '.', '_']; // Exceptions to escaping ranges
         for ($chr = 0; $chr < 0xFF; ++$chr) {
@@ -315,7 +315,7 @@ class EscaperRuntimeTest extends TestCase
         }
     }
 
-    public function testHtmlAttributeEscapingEscapesOwaspRecommendedRanges()
+    public function testHtmlAttributeEscapingEscapesOwaspRecommendedRanges(): void
     {
         $immune = [',', '.', '-', '_']; // Exceptions to escaping ranges
         for ($chr = 0; $chr < 0xFF; ++$chr) {
@@ -338,7 +338,7 @@ class EscaperRuntimeTest extends TestCase
         }
     }
 
-    public function testHtmlAttributeRelaxedEscapingEscapesOwaspRecommendedRanges()
+    public function testHtmlAttributeRelaxedEscapingEscapesOwaspRecommendedRanges(): void
     {
         $immune = [',', '.', '-', '_', ':', '@', '[', ']']; // Exceptions to escaping ranges
         for ($chr = 0; $chr < 0xFF; ++$chr) {
@@ -358,7 +358,7 @@ class EscaperRuntimeTest extends TestCase
         }
     }
 
-    public function testCssEscapingEscapesOwaspRecommendedRanges()
+    public function testCssEscapingEscapesOwaspRecommendedRanges(): void
     {
         // CSS has no exceptions to escaping ranges
         for ($chr = 0; $chr < 0xFF; ++$chr) {
@@ -377,7 +377,7 @@ class EscaperRuntimeTest extends TestCase
         }
     }
 
-    public function testUnknownCustomEscaper()
+    public function testUnknownCustomEscaper(): void
     {
         $this->expectException(RuntimeError::class);
 
@@ -388,7 +388,7 @@ class EscaperRuntimeTest extends TestCase
      * @dataProvider provideCustomEscaperCases
      */
     #[DataProvider('provideCustomEscaperCases')]
-    public function testCustomEscaper($expected, $string, $strategy, $charset)
+    public function testCustomEscaper($expected, $string, $strategy, $charset): void
     {
         $escaper = new EscaperRuntime();
         $escaper->setEscaper('foo', 'Twig\Tests\Runtime\escaper');
@@ -408,7 +408,7 @@ class EscaperRuntimeTest extends TestCase
      * @dataProvider provideObjectsForEscaping
      */
     #[DataProvider('provideObjectsForEscaping')]
-    public function testObjectEscaping(string $escapedHtml, string $escapedJs, array $safeClasses)
+    public function testObjectEscaping(string $escapedHtml, string $escapedJs, array $safeClasses): void
     {
         $obj = new Extension_TestClass();
         $escaper = new EscaperRuntime();
diff --git a/tests/SourceTest.php b/tests/SourceTest.php
index 3064f2cc9..868bd3baf 100644
--- a/tests/SourceTest.php
+++ b/tests/SourceTest.php
@@ -16,7 +16,7 @@ use Twig\Source;
 
 class SourceTest extends TestCase
 {
-    public function testGetColumn()
+    public function testGetColumn(): void
     {
         $source = new Source("foo\nbarbaz\nqux", 'index');
 
diff --git a/tests/TemplateTest.php b/tests/TemplateTest.php
index 79580ff40..527880955 100644
--- a/tests/TemplateTest.php
+++ b/tests/TemplateTest.php
@@ -35,7 +35,7 @@ use Twig\TemplateWrapper;
 
 class TemplateTest extends TestCase
 {
-    public function testDisplayBlocksAcceptTemplateOnlyAsBlocks()
+    public function testDisplayBlocksAcceptTemplateOnlyAsBlocks(): void
     {
         $twig = new Environment(new ArrayLoader());
         $template = new TemplateForTest($twig);
@@ -48,7 +48,7 @@ class TemplateTest extends TestCase
      * @dataProvider getAttributeExceptions
      */
     #[DataProvider('getAttributeExceptions')]
-    public function testGetAttributeExceptions($template, $message)
+    public function testGetAttributeExceptions($template, $message): void
     {
         $templates = ['index' => $template];
         $env = new Environment(new ArrayLoader($templates), ['strict_variables' => true]);
@@ -99,7 +99,7 @@ class TemplateTest extends TestCase
      * @dataProvider getGetAttributeWithSandbox
      */
     #[DataProvider('getGetAttributeWithSandbox')]
-    public function testGetAttributeWithSandbox($object, $item, $allowed)
+    public function testGetAttributeWithSandbox($object, $item, $allowed): void
     {
         $twig = new Environment(new ArrayLoader());
         $policy = new SecurityPolicy([], [], [/* method */], [/* prop */], []);
@@ -139,7 +139,7 @@ class TemplateTest extends TestCase
      * @dataProvider getRenderTemplateWithoutOutputData
      */
     #[DataProvider('getRenderTemplateWithoutOutputData')]
-    public function testRenderTemplateWithoutOutput(string $template)
+    public function testRenderTemplateWithoutOutput(string $template): void
     {
         $twig = new Environment(new ArrayLoader(['index' => $template]));
         $this->assertSame('', $twig->render('index'));
@@ -158,7 +158,7 @@ class TemplateTest extends TestCase
      * @dataProvider getNullCoalesceWithImportedMacroData
      */
     #[DataProvider('getNullCoalesceWithImportedMacroData')]
-    public function testNullCoalesceWithImportedMacro(array $templates, string $expected)
+    public function testNullCoalesceWithImportedMacro(array $templates, string $expected): void
     {
         $twig = new Environment(new ArrayLoader($templates));
 
@@ -192,7 +192,7 @@ class TemplateTest extends TestCase
         ];
     }
 
-    public function testRenderBlockWithUndefinedBlock()
+    public function testRenderBlockWithUndefinedBlock(): void
     {
         $twig = new Environment(new ArrayLoader());
         $template = new TemplateForTest($twig, 'index.twig');
@@ -203,7 +203,7 @@ class TemplateTest extends TestCase
         $template->renderBlock('unknown', []);
     }
 
-    public function testDisplayBlockWithUndefinedBlock()
+    public function testDisplayBlockWithUndefinedBlock(): void
     {
         $twig = new Environment(new ArrayLoader());
         $template = new TemplateForTest($twig, 'index.twig');
@@ -214,7 +214,7 @@ class TemplateTest extends TestCase
         $template->displayBlock('unknown', []);
     }
 
-    public function testDisplayBlockWithUndefinedParentBlock()
+    public function testDisplayBlockWithUndefinedParentBlock(): void
     {
         $twig = new Environment(new ArrayLoader());
         $template = new TemplateForTest($twig, 'parent.twig');
@@ -225,7 +225,7 @@ class TemplateTest extends TestCase
         $template->displayBlock('foo', [], ['foo' => [new TemplateForTest($twig, 'index.twig'), 'block_foo']], false);
     }
 
-    public function testGetAttributeOnArrayWithConfusableKey()
+    public function testGetAttributeOnArrayWithConfusableKey(): void
     {
         $twig = new Environment(new ArrayLoader());
         $template = new TemplateForTest($twig);
@@ -261,7 +261,7 @@ class TemplateTest extends TestCase
      * @dataProvider getStrictVariablesModes
      */
     #[DataProvider('getStrictVariablesModes')]
-    public function testArrayAccessWithStringableKeyIsConsistentAcrossStrictModes(bool $strict)
+    public function testArrayAccessWithStringableKeyIsConsistentAcrossStrictModes(bool $strict): void
     {
         $twig = new Environment(new ArrayLoader(['index' => '{{ array[object] }}']), [
             'strict_variables' => $strict,
@@ -288,7 +288,7 @@ class TemplateTest extends TestCase
      * @dataProvider getStrictVariablesModes
      */
     #[DataProvider('getStrictVariablesModes')]
-    public function testArrayAccessWithObjectKeyKeepsTheObjectKey(bool $strict)
+    public function testArrayAccessWithObjectKeyKeepsTheObjectKey(bool $strict): void
     {
         $twig = new Environment(new ArrayLoader(['index' => '{{ data[object] }}']), [
             'strict_variables' => $strict,
@@ -307,7 +307,7 @@ class TemplateTest extends TestCase
         $this->assertSame('value', $twig->render('index', ['data' => $data, 'object' => $object]));
     }
 
-    public function testArrayAccessWithStringableKeyIsCheckedBySandbox()
+    public function testArrayAccessWithStringableKeyIsCheckedBySandbox(): void
     {
         $object = new class implements \Stringable {
             public function __toString(): string
@@ -337,7 +337,7 @@ class TemplateTest extends TestCase
      * @dataProvider getGetAttributeTests
      */
     #[DataProvider('getGetAttributeTests')]
-    public function testGetAttribute($defined, $value, $object, $item, $arguments, $type)
+    public function testGetAttribute($defined, $value, $object, $item, $arguments, $type): void
     {
         $twig = new Environment(new ArrayLoader());
         $template = new TemplateForTest($twig);
@@ -349,7 +349,7 @@ class TemplateTest extends TestCase
      * @dataProvider getGetAttributeTests
      */
     #[DataProvider('getGetAttributeTests')]
-    public function testGetAttributeStrict($defined, $value, $object, $item, $arguments, $type, $exceptionMessage = null)
+    public function testGetAttributeStrict($defined, $value, $object, $item, $arguments, $type, $exceptionMessage = null): void
     {
         $twig = new Environment(new ArrayLoader(), ['strict_variables' => true]);
         $template = new TemplateForTest($twig);
@@ -369,7 +369,7 @@ class TemplateTest extends TestCase
      * @dataProvider getGetAttributeTests
      */
     #[DataProvider('getGetAttributeTests')]
-    public function testGetAttributeDefined($defined, $value, $object, $item, $arguments, $type)
+    public function testGetAttributeDefined($defined, $value, $object, $item, $arguments, $type): void
     {
         $twig = new Environment(new ArrayLoader());
         $template = new TemplateForTest($twig);
@@ -381,7 +381,7 @@ class TemplateTest extends TestCase
      * @dataProvider getGetAttributeTests
      */
     #[DataProvider('getGetAttributeTests')]
-    public function testGetAttributeDefinedStrict($defined, $value, $object, $item, $arguments, $type)
+    public function testGetAttributeDefinedStrict($defined, $value, $object, $item, $arguments, $type): void
     {
         $twig = new Environment(new ArrayLoader(), ['strict_variables' => true]);
         $template = new TemplateForTest($twig);
@@ -389,7 +389,7 @@ class TemplateTest extends TestCase
         $this->assertEquals($defined, CoreExtension::getAttribute($twig, $template->getSourceContext(), $object, $item, $arguments, $type, true));
     }
 
-    public function testGetAttributeCallExceptions()
+    public function testGetAttributeCallExceptions(): void
     {
         $twig = new Environment(new ArrayLoader());
         $template = new TemplateForTest($twig);
@@ -402,7 +402,7 @@ class TemplateTest extends TestCase
     /**
      * @dataProvider provideNonStringPrintValues
      */
-    public function testPrintingANonStringReportsTheErrorAtThePrintLocation($value, string $expectedMessage)
+    public function testPrintingANonStringReportsTheErrorAtThePrintLocation($value, string $expectedMessage): void
     {
         $twig = new Environment(new ArrayLoader(['index' => "foo\n{{ value }}\nbar"]));
 
@@ -568,7 +568,7 @@ class TemplateTest extends TestCase
         return $tests;
     }
 
-    public function testGetIsMethods()
+    public function testGetIsMethods(): void
     {
         $twig = new Environment(new ArrayLoader());
 
@@ -635,7 +635,7 @@ class TemplateForTest extends Template
     {
     }
 
-    public function block_name($context, array $blocks = [])
+    public function block_name($context, array $blocks = []): void
     {
     }
 }
@@ -799,7 +799,7 @@ class TemplateMethodObject
         return 0;
     }
 
-    public function getNull()
+    public function getNull(): void
     {
     }
 
@@ -856,11 +856,11 @@ class TemplateMethodObject
 
 class TemplateGetIsMethods
 {
-    public function get()
+    public function get(): void
     {
     }
 
-    public function is()
+    public function is(): void
     {
     }
 }
@@ -928,7 +928,7 @@ class TemplateMagicMethodObject
 
 class TemplateMagicMethodExceptionObject
 {
-    public function __call($method, $arguments)
+    public function __call($method, $arguments): void
     {
         throw new \BadMethodCallException(\sprintf('Unknown method "%s".', $method));
     }
diff --git a/tests/TemplateWrapperTest.php b/tests/TemplateWrapperTest.php
index 73e0cd178..475c22e68 100644
--- a/tests/TemplateWrapperTest.php
+++ b/tests/TemplateWrapperTest.php
@@ -26,7 +26,7 @@ use Twig\Loader\ArrayLoader;
 
 class TemplateWrapperTest extends TestCase
 {
-    public function testHasGetBlocks()
+    public function testHasGetBlocks(): void
     {
         $twig = new Environment(new ArrayLoader([
             'index' => '{% block foo %}{% endblock %}',
@@ -52,7 +52,7 @@ class TemplateWrapperTest extends TestCase
         $this->assertEquals(['foo', 'extended'], $wrapper->getBlockNames());
     }
 
-    public function testRenderBlock()
+    public function testRenderBlock(): void
     {
         $twig = new Environment(new ArrayLoader([
             'index' => '{% block foo %}{{ foo }}{{ bar }}{% endblock %}',
@@ -63,7 +63,7 @@ class TemplateWrapperTest extends TestCase
         $this->assertEquals('FOOBAR', $wrapper->renderBlock('foo', ['foo' => 'FOO']));
     }
 
-    public function testDisplayBlock()
+    public function testDisplayBlock(): void
     {
         $twig = new Environment(new ArrayLoader([
             'index' => '{% block foo %}{{ foo }}{{ bar }}{% endblock %}',
diff --git a/tests/TokenParser/GuardTokenParserTest.php b/tests/TokenParser/GuardTokenParserTest.php
index 4f6ce9c6d..e8c87f07c 100644
--- a/tests/TokenParser/GuardTokenParserTest.php
+++ b/tests/TokenParser/GuardTokenParserTest.php
@@ -20,7 +20,7 @@ use Twig\Source;
 
 class GuardTokenParserTest extends TestCase
 {
-    public function testUndefinedHandlers()
+    public function testUndefinedHandlers(): void
     {
         $this->expectNotToPerformAssertions();
 
diff --git a/tests/TokenStreamTest.php b/tests/TokenStreamTest.php
index d1c93220e..39025dd5a 100644
--- a/tests/TokenStreamTest.php
+++ b/tests/TokenStreamTest.php
@@ -44,7 +44,7 @@ class TokenStreamTest extends TestCase
         ];
     }
 
-    public function testNext()
+    public function testNext(): void
     {
         $stream = new TokenStream(self::$tokens, new Source('', ''));
         $repr = [];
@@ -56,7 +56,7 @@ class TokenStreamTest extends TestCase
         $this->assertEquals('1, 2, 3, 4, 5, 6, 7', implode(', ', $repr), '->next() advances the pointer and returns the current token');
     }
 
-    public function testEndOfTemplateNext()
+    public function testEndOfTemplateNext(): void
     {
         $stream = new TokenStream([
             new Token(Token::BLOCK_START_TYPE, 1, 1),
@@ -70,7 +70,7 @@ class TokenStreamTest extends TestCase
         }
     }
 
-    public function testEndOfTemplateLook()
+    public function testEndOfTemplateLook(): void
     {
         $stream = new TokenStream([
             new Token(Token::BLOCK_START_TYPE, 1, 1),
diff --git a/tests/Util/CallableArgumentsExtractorTest.php b/tests/Util/CallableArgumentsExtractorTest.php
index aa542c316..348330794 100644
--- a/tests/Util/CallableArgumentsExtractorTest.php
+++ b/tests/Util/CallableArgumentsExtractorTest.php
@@ -38,12 +38,12 @@ class CallableArgumentsExtractorTest extends TestCase
 {
     use ExpectDeprecationTrait;
 
-    public function testGetArguments()
+    public function testGetArguments(): void
     {
         $this->assertEquals(['U', null], $this->getArguments('date', 'date', ['format' => 'U', 'timestamp' => null]));
     }
 
-    public function testGetArgumentsWhenPositionalArgumentsAfterNamedArguments()
+    public function testGetArgumentsWhenPositionalArgumentsAfterNamedArguments(): void
     {
         $this->expectException(SyntaxError::class);
         $this->expectExceptionMessage('Positional arguments cannot be used after named arguments for function "date" in "test.twig" at line 2.');
@@ -51,7 +51,7 @@ class CallableArgumentsExtractorTest extends TestCase
         $this->getArguments('date', 'date', ['timestamp' => 123456, 'Y-m-d']);
     }
 
-    public function testGetArgumentsWhenArgumentIsDefinedTwice()
+    public function testGetArgumentsWhenArgumentIsDefinedTwice(): void
     {
         $this->expectException(SyntaxError::class);
         $this->expectExceptionMessage('Argument "format" is defined twice for function "date" in "test.twig" at line 2.');
@@ -59,7 +59,7 @@ class CallableArgumentsExtractorTest extends TestCase
         $this->getArguments('date', 'date', ['Y-m-d', 'format' => 'U']);
     }
 
-    public function testGetArgumentsWithWrongNamedArgumentName()
+    public function testGetArgumentsWithWrongNamedArgumentName(): void
     {
         $this->expectException(SyntaxError::class);
         $this->expectExceptionMessage('Unknown argument "unknown" for function "date(format, timestamp)".');
@@ -67,7 +67,7 @@ class CallableArgumentsExtractorTest extends TestCase
         $this->getArguments('date', 'date', ['Y-m-d', 'timestamp' => null, 'unknown' => '']);
     }
 
-    public function testGetArgumentsWithWrongNamedArgumentNames()
+    public function testGetArgumentsWithWrongNamedArgumentNames(): void
     {
         $this->expectException(SyntaxError::class);
         $this->expectExceptionMessage('Unknown arguments "unknown1", "unknown2" for function "date(format, timestamp)".');
@@ -75,7 +75,7 @@ class CallableArgumentsExtractorTest extends TestCase
         $this->getArguments('date', 'date', ['Y-m-d', 'timestamp' => null, 'unknown1' => '', 'unknown2' => '']);
     }
 
-    public function testResolveArgumentsWithMissingValueForOptionalArgument()
+    public function testResolveArgumentsWithMissingValueForOptionalArgument(): void
     {
         if (\PHP_VERSION_ID >= 80000) {
             $this->markTestSkipped('substr_compare() has a default value in 8.0, so the test does not work anymore, one should find another PHP built-in function for this test to work in PHP 8.');
@@ -87,12 +87,12 @@ class CallableArgumentsExtractorTest extends TestCase
         $this->getArguments('substr_compare', 'substr_compare', ['abcd', 'bc', 'offset' => 1, 'case_sensitivity' => true]);
     }
 
-    public function testResolveArgumentsOnlyNecessaryArgumentsForCustomFunction()
+    public function testResolveArgumentsOnlyNecessaryArgumentsForCustomFunction(): void
     {
         $this->assertEquals(['arg1'], $this->getArguments('custom_function', [$this, 'customFunction'], ['arg1' => 'arg1']));
     }
 
-    public function testGetArgumentsForStaticMethod()
+    public function testGetArgumentsForStaticMethod(): void
     {
         $this->assertEquals(['arg1'], $this->getArguments('custom_static_function', __CLASS__.'::customStaticFunction', ['arg1' => 'arg1']));
     }
@@ -101,7 +101,7 @@ class CallableArgumentsExtractorTest extends TestCase
      * @dataProvider getGetArgumentsConversionData
      */
     #[DataProvider('getGetArgumentsConversionData')]
-    public function testGetArgumentsConversion($arg1, $arg2)
+    public function testGetArgumentsConversion($arg1, $arg2): void
     {
         $this->assertEquals([null], $this->getArguments('custom', eval("return fn (\$$arg1) => '';"), [$arg1 => null]));
         $this->assertEquals([null], $this->getArguments('custom', eval("return fn (\$$arg2) => '';"), [$arg2 => null]));
@@ -125,7 +125,7 @@ class CallableArgumentsExtractorTest extends TestCase
      * @group legacy
      */
     #[Group('legacy')]
-    public function testGetArgumentsConversionForVariadics()
+    public function testGetArgumentsConversionForVariadics(): void
     {
         $this->expectDeprecation('Since twig/twig 3.15: Using "snake_case" for variadic arguments is required for a smooth upgrade with Twig 4.0; rename "someNumberVariadic" to "some_number_variadic" in "test.twig" at line 2.');
 
@@ -139,7 +139,7 @@ class CallableArgumentsExtractorTest extends TestCase
         ], $this->getArguments('custom', eval("return fn (string \$someText, int \$some_number, ...\$args) => '';"), ['some_text' => 'a', 'someNumber' => 12, 'some_text_variadic' => 'a', 'someNumberVariadic' => 12], true));
     }
 
-    public function testGetArgumentsError()
+    public function testGetArgumentsError(): void
     {
         $this->expectException(SyntaxError::class);
         $this->expectExceptionMessage('Value for argument "some_name" is required for function "custom_static_function" in "test.twig" at line 2.');
@@ -147,7 +147,7 @@ class CallableArgumentsExtractorTest extends TestCase
         $this->getArguments('custom_static_function', [$this, 'customFunctionSnakeCamel'], ['someCity' => 'Paris']);
     }
 
-    public function testResolveArgumentsWithMissingParameterForArbitraryArguments()
+    public function testResolveArgumentsWithMissingParameterForArbitraryArguments(): void
     {
         $this->expectException(SyntaxError::class);
         $this->expectExceptionMessage('The last parameter of "Twig\\Tests\\Util\\CallableArgumentsExtractorTest::customFunctionWithArbitraryArguments" for function "foo" must be an array with default value, eg. "array $arg = []".');
@@ -155,14 +155,14 @@ class CallableArgumentsExtractorTest extends TestCase
         $this->getArguments('foo', [$this, 'customFunctionWithArbitraryArguments'], [], true);
     }
 
-    public function testGetArgumentsWithInvalidCallable()
+    public function testGetArgumentsWithInvalidCallable(): void
     {
         $this->expectException(\LogicException::class);
         $this->expectExceptionMessage('Callback for function "foo" is not callable in the current scope.');
         $this->getArguments('foo', '<not-a-callable>', [], true);
     }
 
-    public function testResolveArgumentsWithMissingParameterForArbitraryArgumentsOnFunction()
+    public function testResolveArgumentsWithMissingParameterForArbitraryArgumentsOnFunction(): void
     {
         $this->expectException(SyntaxError::class);
         $this->expectExceptionMessageMatches('#^The last parameter of "Twig\\\\Tests\\\\Util\\\\custom_call_test_function" for function "foo" must be an array with default value, eg\\. "array \\$arg \\= \\[\\]"\\.$#');
@@ -170,7 +170,7 @@ class CallableArgumentsExtractorTest extends TestCase
         $this->getArguments('foo', 'Twig\Tests\Util\custom_call_test_function', [], true);
     }
 
-    public function testResolveArgumentsWithMissingParameterForArbitraryArgumentsOnObject()
+    public function testResolveArgumentsWithMissingParameterForArbitraryArgumentsOnObject(): void
     {
         $this->expectException(SyntaxError::class);
         $this->expectExceptionMessageMatches('#^The last parameter of "Twig\\\\Tests\\\\Util\\\\CallableTestClass\\:\\:__invoke" for function "foo" must be an array with default value, eg\\. "array \\$arg \\= \\[\\]"\\.$#');
@@ -178,19 +178,19 @@ class CallableArgumentsExtractorTest extends TestCase
         $this->getArguments('foo', new CallableTestClass(), [], true);
     }
 
-    public static function customStaticFunction($arg1, $arg2 = 'default', $arg3 = [])
+    public static function customStaticFunction($arg1, $arg2 = 'default', $arg3 = []): void
     {
     }
 
-    public function customFunction($arg1, $arg2 = 'default', $arg3 = [])
+    public function customFunction($arg1, $arg2 = 'default', $arg3 = []): void
     {
     }
 
-    public function customFunctionSnakeCamel($someName, $some_city)
+    public function customFunctionSnakeCamel($someName, $some_city): void
     {
     }
 
-    public function customFunctionWithArbitraryArguments()
+    public function customFunctionWithArbitraryArguments(): void
     {
     }
 
@@ -218,11 +218,11 @@ class ExpressionCall extends FunctionExpression
 
 class CallableTestClass
 {
-    public function __invoke($required)
+    public function __invoke($required): void
     {
     }
 }
 
-function custom_call_test_function($required)
+function custom_call_test_function($required): void
 {
 }
diff --git a/tests/Util/DeprecationCollectorTest.php b/tests/Util/DeprecationCollectorTest.php
index 5a39e0413..333c74882 100644
--- a/tests/Util/DeprecationCollectorTest.php
+++ b/tests/Util/DeprecationCollectorTest.php
@@ -29,7 +29,7 @@ use Twig\Util\DeprecationCollector;
 
 class DeprecationCollectorTest extends TestCase
 {
-    public function testCollect()
+    public function testCollect(): void
     {
         $twig = new Environment(new ArrayLoader());
         $twig->addFunction(new TwigFunction('deprec', [$this, 'deprec'], ['deprecation_info' => new DeprecatedCallableInfo('foo/bar', '1.1')]));
@@ -40,7 +40,7 @@ class DeprecationCollectorTest extends TestCase
         $this->assertEquals(['Since foo/bar 1.1: Twig Function "deprec" is deprecated in deprec.twig at line 1.'], $deprecations);
     }
 
-    public function deprec()
+    public function deprec(): void
     {
     }
 }