How to Call command line from TestCase in Laravel 5

I am developing an application in Laravel 5, I have a test file which extends from TestCase.php, I need to call the phpcs command in my file

 class MyTest extends TestCase {

    public function testFunction()
    {
        //here I need to call the phpcs command                  
     }
  }

In te examples here http://ift.tt/1AZ471p I just found the this->call function, which I don't think is the proper choice for me, since it is returning a response object, what is the right way to do it? which Class and functions should I use to to run a command-line inside this class?