Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in /home/rosengar/Lib/composerRosengartPHP8/vendor/slim/psr7/tests/MessageTest.php:21 Stack trace: #0 {main} thrown in /home/rosengar/Lib/composerRosengartPHP8/vendor/slim/psr7/tests/MessageTest.php on line 21