title: How to attach a file using SubmitForm() in Codeception
body: <p>I'm testing a form through the <code>SubmitForm()</code> function because the form uses javascript to cycle through each individual item. </p>
  
  <p><strong>example:</strong></p>
  
  <pre><code>$I-&gt;submitForm('#form', array(
      'feet' =&gt; '1',
      'inches' =&gt; '2',
  
  ), 'submit');
  </code></pre>
  
  <p>This works fine but I'm having trouble with a file upload input. </p>
  
  <pre><code>$I-&gt;submitForm('#form', array(
      'feet' =&gt; '1',
      'inches' =&gt; '2',
      'file' =&gt; ???
  
   ), 'submit');
  </code></pre>
  
  <p>I tried sending an array to mimic the <code>$_FILES</code> array but that obviously isn't the right way to do it. Is this possible?</p>