'Register a mock response for POST on the CS comments endpoint for the
given thread or parent; exactly one of thread_id and parent_id must be
specified.'

def register_post_comment_response(self, comment_data, thread_id, parent_id=None):

    if parent_id:
        url = u'http://localhost:4567/api/v1/comments/{}'.format(parent_id)
    else:
        url = u'http://localhost:4567/api/v1/threads/{}/comments'.format(thread_id)
    httpretty.register_uri(httpretty.POST, url, body=_get_comment_callback(comment_data, thread_id, parent_id))
