def namesTest(self, querying, expectedRecords):
        """
        Assert that the DNS response C{querying} will eventually fire with
        contains exactly a certain collection of records.

        @param querying: A L{Deferred} returned from one of the DNS client
            I{lookup} methods.

        @param expectedRecords: A L{list} of L{IRecord} providers which must be
            in the response or the test will be failed.

        @return: A L{Deferred} that fires when the assertion has been made.  It
            fires with a success result if the assertion succeeds and with a
            L{Failure} if it fails.
        """
        def checkResults(response):
            receivedRecords = justPayload(response)
            self.assertEqual(set(expectedRecords), set(receivedRecords))

        querying.addCallback(checkResults)
        return querying

        Assert that the DNS response C{querying} will eventually fire with
        contains exactly a certain collection of records.

        @param querying: A L{Deferred} returned from one of the DNS client
            I{lookup} methods.

        @param expectedRecords: A L{list} of L{IRecord} providers which must be
            in the response or the test will be failed.

        @return: A L{Deferred} that fires when the assertion has been made.  It
            fires with a success result if the assertion succeeds and with a
            L{Failure} if it fails.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_names.py