title: Get the CSRF token in test
body: <p>I'm writing functional test and i need to make ajax post request. <strong>"The CSRF token is invalid. Please try to resubmit the form"</strong>. How can i get the token in my functional test ?</p>
  
  <pre><code>$crawler = $this-&gt;client-&gt;request(
    'POST', 
    $url, 
    array(
        'element_add' =&gt; array(
            '_token' =&gt; '????',
            'name'   =&gt; 'bla',
        )
  
    ), 
    array(), 
    array('HTTP_X-Requested-With' =&gt; 'XMLHttpRequest')
  );
  </code></pre>