def test_getChildWithDefault(self):
        """
        When getChildWithDefault is invoked, it adds the headers to the
        response.
        """
        resource = _AddHeadersResource(
            demo.Test(), [("K1", "V1"), ("K2", "V2"), ("K1", "V3")])
        request = DummyRequest([])
        resource.getChildWithDefault("", request)
        self.assertEqual(
            request.responseHeaders.getRawHeaders("K1"), ["V1", "V3"])
        self.assertEqual(request.responseHeaders.getRawHeaders("K2"), ["V2"])

        When getChildWithDefault is invoked, it adds the headers to the
        response.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_tap.py