def test_recursiveConfiguration(self):
        options = Options()
        options.parseOptions(['--hosts-file', 'hosts.txt', '--recursive'])
        ca, cl = _buildResolvers(options)

        # Extra cleanup, necessary on POSIX because client.Resolver doesn't know
        # when to stop parsing resolv.conf.  See #NNN for improving this.
        for x in cl:
            if isinstance(x, ResolverChain):
                recurser = x.resolvers[-1]
                if isinstance(recurser, Resolver):
                    recurser._parseCall.cancel()

        self.assertIsInstance(cl[-1], ResolverChain)
Recursive DNS lookups, if enabled, should be a last-resort option.
dataset/ETHPy150Open nlloyd/SubliminalCollaborator/libs/twisted/names/test/test_tap.py/OptionsTests.test_recursiveConfiguration