Adding a test case for caching template class to the filesystem.

test/Twig/Tests/FileCachingTest.php

@@ -0,0 +1,37 @@
+<?php
+
+class Twig_Tests_FileCachingTest extends PHPUnit_Framework_TestCase
+{
+    protected $fileName;
+    protected $tmpDir;
+
+    function setUp()
+    {
+        $this->tmpDir = sys_get_temp_dir();
+        if (!is_writable($this->tmpDir)) {
+            $this->markTestSkipped(sprintf('Cannot write to %s, cannot test file caching.', $this->tmpDir));
+        }
+        parent::setUp();
+    }
+    
+    function testWritingCacheFiles()
+    {
+        $loader = new Twig_Loader_String();
+        $env = new Twig_Environment($loader, array('cache' => $this->tmpDir));
+
+        $name = 'This is just text.';
+        $template = $env->loadTemplate($name);
+        $cacheFileName = $env->getCacheFilename($name);
+
+        $this->assertTrue(file_exists($cacheFileName), 'Cache file does not exist.');
+        $this->fileName = $cacheFileName;
+    }
+
+    function tearDown()
+    {
+        if($this->fileName) {
+            unlink($this->fileName);
+        }
+        parent::tearDown();
+    }
+}