Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in C:\xampp\htdocs\pagina\laravel_backend_app\vendor\guzzlehttp\guzzle\tests\Handler\ProxyEnvironmentTest.php:11 Stack trace: #0 {main} thrown in C:\xampp\htdocs\pagina\laravel_backend_app\vendor\guzzlehttp\guzzle\tests\Handler\ProxyEnvironmentTest.php on line 11