title: I want to integrate getContainer() in WebTestCase
body: <pre><code>use Liip\FunctionalTestBundle\Test\WebTestCase;
  
  class ControllerTest extends WebTestCase
  {
      public function testSuccess()
      {
          $url = $this-&gt;getContainer()-&gt;get('router')
              -&gt;generate('name_route', array('parameter' =&gt; ' '));
  
          $this-&gt;client-&gt;request('GET', $url,
              array(),
              array(),
              array(
                  'HTTP_parameter_Header' =&gt; 'paramterHeader',          
              )
          );
      }
  }
  </code></pre>
  
  <p>After I launched the test, I have an error: </p>
  
  <blockquote>
    <p>Call to a member function getContainer() on a non-object</p>
  </blockquote>