Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\xampp\htdocs\smsgateway\tests\Unit\Domain\Messaging\SenderIdValidatorTest.php:13 Stack trace: #0 {main} thrown in C:\xampp\htdocs\smsgateway\tests\Unit\Domain\Messaging\SenderIdValidatorTest.php on line 13