def test_badAncillaryNext(self):
        """
        If iteration over the ancillary data list fails (at the point of a
        C{next} call), the exception with which it fails is propagated to the
        caller of L{send1msg}.
        """
        worseList = WorseList()
        self.assertRaises(RuntimeError, send1msg,
                          1, "hello world", 2,worseList)

        If iteration over the ancillary data list fails (at the point of a
        C{next} call), the exception with which it fails is propagated to the
        caller of L{send1msg}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_sendmsg.py