def test_interfaceInheritance(self):
        """
        Proxies of subinterfaces generated with proxyForInterface should allow
        access to attributes of both the child and the base interfaces.
        """
        proxyClass = proxyForInterface(IProxiedSubInterface)
        booable = Booable()
        proxy = proxyClass(booable)
        proxy.yay()
        proxy.boo()
        self.assertTrue(booable.yayed)
        self.assertTrue(booable.booed)

        Proxies of subinterfaces generated with proxyForInterface should allow
        access to attributes of both the child and the base interfaces.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_components.py