def test_clientAddrUnknown(self):
        """
        A request made from an unknown address type is logged as C{"-"}.
        """
        @implementer(interfaces.IAddress)
        class UnknowableAddress(object):
            """
            An L{IAddress} which L{combinedLogFormatter} cannot have
            foreknowledge of.
            """

        reactor = Clock()
        reactor.advance(1234567890)

        timestamp = http.datetimeToLogString(reactor.seconds())
        request = DummyRequestForLogTest(http.HTTPFactory(reactor=reactor))
        request.client = UnknowableAddress()

        line = http.combinedLogFormatter(timestamp, request)
        self.assertTrue(line.startswith(u'"-" '))

        A request made from an unknown address type is logged as C{"-"}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_web.py