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