Fatal error: Uncaught Error: Class 'PHPUnit\Framework\TestCase' not found in /home/adm.sch/vendor/guzzlehttp/guzzle/tests/Handler/MockHandlerTest.php:14 Stack trace: #0 {main} thrown in /home/adm.sch/vendor/guzzlehttp/guzzle/tests/Handler/MockHandlerTest.php on line 14