def _referralTest(self, method):
        """
        Create an authority and make a request against it.  Then verify that the
        result is a referral, including no records in the answers or additional
        sections, but with an I{NS} record in the authority section.
        """
        subdomain = 'example.' + str(soa_record.mname)
        nameserver = dns.Record_NS('1.2.3.4')
        authority = NoFileAuthority(
            soa=(str(soa_record.mname), soa_record),
            records={
                subdomain: [
                    nameserver,
                    ]})
        d = getattr(authority, method)(subdomain)
        answer, authority, additional = self.successResultOf(d)
        self.assertEqual(answer, [])
        self.assertEqual(
            authority, [dns.RRHeader(
                    subdomain, dns.NS, ttl=soa_record.expire,
                    payload=nameserver, auth=False)])
        self.assertEqual(additional, [])

        Create an authority and make a request against it.  Then verify that the
        result is a referral, including no records in the answers or additional
        sections, but with an I{NS} record in the authority section.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_names.py