Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\xampp\htdocs\smsgateway2\tests\Unit\Infrastructure\Smpp\Protocol\DeliverSmTest.php:20 Stack trace: #0 {main} thrown in C:\xampp\htdocs\smsgateway2\tests\Unit\Infrastructure\Smpp\Protocol\DeliverSmTest.php on line 20