Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\xampp\htdocs\sitelec-ib.ddns.net\vendor\symfony\mailer\Test\AbstractTransportFactoryTestCase.php:21 Stack trace: #0 {main} thrown in C:\xampp\htdocs\sitelec-ib.ddns.net\vendor\symfony\mailer\Test\AbstractTransportFactoryTestCase.php on line 21