def test_interfaceCompliance(self):
        """
        L{PluggableResolverMixin} (and its subclasses) implement both
        L{IReactorPluggableNameResolver} and L{IReactorPluggableResolver}.
        """
        reactor = PluggableResolverMixin()
        verifyObject(IReactorPluggableNameResolver, reactor)
        verifyObject(IResolverSimple, reactor.resolver)
        verifyObject(IHostnameResolver, reactor.nameResolver)

        L{PluggableResolverMixin} (and its subclasses) implement both
        L{IReactorPluggableNameResolver} and L{IReactorPluggableResolver}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_resolver.py