'Successful POSTs return a 200 and JSON of the form {"result": "success",
"msg": ""}.'

def assert_json_success(self, result):

    self.assertEqual(result.status_code, 200, result)
    json = ujson.loads(result.content)
    self.assertEqual(json.get('result'), 'success')
    self.assertIn('msg', json)
    return json
