Fatal error: Uncaught Error: Class 'PHPUnit\Framework\TestCase' not found in E:\xampp\htdocs\www\key\vendor\symfony\debug\Tests\Exception\FlattenExceptionTest.php:32 Stack trace: #0 {main} thrown in E:\xampp\htdocs\www\key\vendor\symfony\debug\Tests\Exception\FlattenExceptionTest.php on line 32