Fixed Route::setUrl() behavior

When there are no parameters in the url, correctly empty the routes parameter array

tests/Pecee/SimpleRouter/Dummy/Route/DummyLoadableRoute.php

@@ -0,0 +1,11 @@
+<?php
+
+use Pecee\Http\Request;
+
+class DummyLoadableRoute extends Pecee\SimpleRouter\Route\LoadableRoute {
+
+    public function matchRoute(string $url, Request $request): bool
+    {
+        return false;
+    }
+}

tests/Pecee/SimpleRouter/LoadableRouteTest.php

@@ -0,0 +1,27 @@
+<?php
+
+require_once 'Dummy/Route/DummyLoadableRoute.php';
+
+class LoadableRouteTest extends \PHPUnit\Framework\TestCase
+{
+    public function testSetUrlUpdatesParameters()
+    {
+        $route = new DummyLoadableRoute();
+        $this->assertEmpty($route->getParameters());
+
+        $route->setUrl('/');
+        $this->assertEmpty($route->getParameters());
+
+        $expected = ['param' => null, 'optionalParam' => null];
+        $route->setUrl('/{param}/{optionalParam?}');
+        $this->assertEquals($expected, $route->getParameters());
+
+        $expected = ['otherParam' => null];
+        $route->setUrl('/{otherParam}');
+        $this->assertEquals($expected, $route->getParameters());
+
+        $expected = [];
+        $route->setUrl('/');
+        $this->assertEquals($expected, $route->getParameters());
+    }
+}