Fatal error: Uncaught Error: Class 'PHPUnit\Framework\TestCase' not found in E:\xampp\htdocs\key1\vendor\symfony\event-dispatcher\Tests\EventDispatcherTest.php:20 Stack trace: #0 {main} thrown in E:\xampp\htdocs\key1\vendor\symfony\event-dispatcher\Tests\EventDispatcherTest.php on line 20