Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\xampp\htdocs\gnu_7\g7\tests\Unit\Installer\ComposerPathValidationTest.php:21 Stack trace: #0 {main} thrown in C:\xampp\htdocs\gnu_7\g7\tests\Unit\Installer\ComposerPathValidationTest.php on line 21