Laravel & TDD: Only test 1 file or function

Hello,

I'm developing with Laravel 5.1 and creating some testing files... http://laravel.com/docs/5.1/testing

I can test all my code executing phpunit inside my project folder but how test only one file/function:

- 1 file: phpunit tests/Auth/UserTest.php
- 1 function: phpunit --filter testRegisterControllerUser tests/Auth/UserTest.php

Best regards,
Iban Cardona.