'If there are no records in the response to a lookup of a delegation
nameserver, the L{Deferred} returned by L{Resolver.lookupAddress} fires
with L{ResolverError}.'

def test_delegationLookupEmpty(self):

    servers = {('1.1.2.3', 53): {('example.com', A): {'authority': [('example.com', Record_NS('ns1.example.com'))]}, ('ns1.example.com', A): {}}}
    resolver = self._getResolver(servers)
    d = resolver.lookupAddress('example.com')
    return self.assertFailure(d, ResolverError)
