Fix typo

tests/Composer/Test/Json/JsonFileTest.php

@@ -87,7 +87,7 @@ class JsonFileTest extends \PHPUnit_Framework_TestCase
 
     public function testSchemaValidation()
     {
-        $json = new JsonFile(__DIR__.'/fixtures/composer.json');
+        $json = new JsonFile(__DIR__.'/Fixtures/composer.json');
         $this->assertTrue($json->validateSchema());
     }