Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in /var/www/html/mun/vendor/ratchet/rfc6455/tests/unit/Messaging/FrameTest.php:13 Stack trace: #0 {main} thrown in /var/www/html/mun/vendor/ratchet/rfc6455/tests/unit/Messaging/FrameTest.php on line 13