Fatal error: Uncaught Error: Class 'PHPUnit\Framework\TestCase' not found in /home/kubalos2/public_html/testtestowy/vendor/sebastian/environment/tests/OperatingSystemTest.php:20 Stack trace: #0 {main} thrown in /home/kubalos2/public_html/testtestowy/vendor/sebastian/environment/tests/OperatingSystemTest.php on line 20