def _compatHeadersTest(self, oldName, newName):
        """
        Verify that each of two different attributes which are associated with
        the same state properly reflect changes made through the other.

        This is used to test that the C{headers}/C{responseHeaders} and
        C{received_headers}/C{requestHeaders} pairs interact properly.
        """
        req = http.Request(DummyChannel(), False)
        getattr(req, newName).setRawHeaders(b"test", [b"lemur"])
        self.assertEqual(getattr(req, oldName)[b"test"], b"lemur")
        setattr(req, oldName, {b"foo": b"bar"})
        self.assertEqual(
            list(getattr(req, newName).getAllRawHeaders()),
            [(b"Foo", [b"bar"])])
        setattr(req, newName, http_headers.Headers())
        self.assertEqual(getattr(req, oldName), {})

        Verify that each of two different attributes which are associated with
        the same state properly reflect changes made through the other.

        This is used to test that the C{headers}/C{responseHeaders} and
        C{received_headers}/C{requestHeaders} pairs interact properly.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_http.py