def test_continuesWhenSomeRootHintsFail(self):
        """
        The L{root.Resolver} is eventually created, even if some of the root
        hint lookups fail. Only the working root hint IP addresses are supplied
        to the L{root.Resolver}.
        """
        stubResolver = StubResolver()
        deferredResolver = root.bootstrap(stubResolver)
        results = iter(stubResolver.pendingResults)
        d1 = next(results)
        for d in results:
            d.callback('192.0.2.101')
        d1.errback(TimeoutError())

        def checkHints(res):
            self.assertEqual(deferredResolver.hints, ['192.0.2.101'] * 12)
        d1.addBoth(checkHints)

        The L{root.Resolver} is eventually created, even if some of the root
        hint lookups fail. Only the working root hint IP addresses are supplied
        to the L{root.Resolver}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_rootresolve.py