Fatal error: Uncaught Error: Class 'PHPUnit\Framework\TestCase' not found in E:\xampp\htdocs\www\key1\vendor\symfony\css-selector\Tests\CssSelectorConverterTest.php:17 Stack trace: #0 {main} thrown in E:\xampp\htdocs\www\key1\vendor\symfony\css-selector\Tests\CssSelectorConverterTest.php on line 17