title: Working authentication in functional testing
body: <p>This example is not working: <a href="http://symfony.com/doc/current/cookbook/testing/simulating_authentication.html" rel="nofollow">http://symfony.com/doc/current/cookbook/testing/simulating_authentication.html</a> </p>
  
  <p>$session = $this->client->getContainer(); in login function return null.
  Is any actual way for functional testing?</p>