Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\xampp\htdocs\CnVideosSite\vendor\topthink\framework\tests\HttpTest.php:21 Stack trace: #0 {main} thrown in C:\xampp\htdocs\CnVideosSite\vendor\topthink\framework\tests\HttpTest.php on line 21