Include $_SERVER['PHP_AUTH_USER'] for all Unit Test with PHPUnit and Laravel 5.1

I'm testing Rest APIs. For all test, I need to define :

    $_SERVER['PHP_AUTH_USER'] = 'email@company.com';
    $_SERVER['PHP_AUTH_PW'] = 'WgYRBz-Z9H9x-27exLt';

I'm sure it is posible to declare just one those variables, and to use it in my unit test, but don't know how!

Any idea?