Fatal error: Uncaught Error: Class 'PHPUnit\Framework\TestCase' not found in E:\xampp\htdocs\www\key\vendor\phpunit\phpunit-mock-objects\tests\MockObjectTest.php:15 Stack trace: #0 {main} thrown in E:\xampp\htdocs\www\key\vendor\phpunit\phpunit-mock-objects\tests\MockObjectTest.php on line 15