Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in /home/mulwnet/beta.mulw.net/vendor/symfony/mime/Tests/Test/Constraint/EmailHasHeaderTest.php:20 Stack trace: #0 {main} thrown in /home/mulwnet/beta.mulw.net/vendor/symfony/mime/Tests/Test/Constraint/EmailHasHeaderTest.php on line 20