def test_getChild(self):
        """
        The L{ReverseProxyResource.getChild} method should return a resource
        instance with the same class as the originating resource, forward
        port, host, and reactor values, and update the path value with the
        value passed.
        """
        reactor = MemoryReactor()
        resource = ReverseProxyResource(u"127.0.0.1", 1234, b"/path", reactor)
        child = resource.getChild(b'foo', None)
        # The child should keep the same class
        self.assertIsInstance(child, ReverseProxyResource)
        self.assertEqual(child.path, b"/path/foo")
        self.assertEqual(child.port, 1234)
        self.assertEqual(child.host, u"127.0.0.1")
        self.assertIdentical(child.reactor, resource.reactor)

        The L{ReverseProxyResource.getChild} method should return a resource
        instance with the same class as the originating resource, forward
        port, host, and reactor values, and update the path value with the
        value passed.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_proxy.py