Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in E:\xampp\htdocs\key1\vendor\symfony\http-kernel\Tests\HttpCache\SsiTest.php:19 Stack trace: #0 {main} thrown in E:\xampp\htdocs\key1\vendor\symfony\http-kernel\Tests\HttpCache\SsiTest.php on line 19