title: Supertest multiple request.field array is undefined on the server
body: <p>I'm writing a unit test with supertest to test my server. But one of my body fields containing an array of json objects 'arrives' undefined.</p>
  
  <p>the code:</p>
  
  <pre><code>//declaration of variable
  tags = [{name: 'tag1'},{name: 'tag2'},{name: 'tag3'}];
  
  //actual post
   agent.post('/pictures')
                  .set('Connection', 'keep alive')
                  .set('Content-Type', 'application/x-www-form-urlencoded')
                  .field('picTitle', 'Picture Title')
                  .field('tags', tags)
                  .attach('file', __dirname + '/img/noel.jpg')
                  .end(function(pictureSaveErr, pictureSaveRes) {
                     //do stuff
                  }
  </code></pre>
  
  <p>So the problem is that req.body.tags at the server is undefined. Strings are no problem. The actual implementation with angular frontend is working perfectly so the problem isn't with the server.</p>
  
  <p>Hope someone can help me out, a big thanks in advance...</p>