Fatal error: Uncaught Error: Class 'PHPUnit\Framework\TestCase' not found in C:\xampp\htdocs\admin\vendor\league\oauth1-client\tests\RsaClientCredentialsTest.php:10 Stack trace: #0 {main} thrown in C:\xampp\htdocs\admin\vendor\league\oauth1-client\tests\RsaClientCredentialsTest.php on line 10