def test_wrappingProtocolFileDescriptorReceiver(self):
        """
        Our L{_WrappingProtocol} should be an L{IFileDescriptorReceiver} if the
        wrapped protocol is.
        """
        connectedDeferred = None
        applicationProtocol = TestFileDescriptorReceiverProtocol()
        wrapper = endpoints._WrappingProtocol(
            connectedDeferred, applicationProtocol)
        self.assertTrue(interfaces.IFileDescriptorReceiver.providedBy(wrapper))
        self.assertTrue(
            verifyObject(interfaces.IFileDescriptorReceiver, wrapper))

        Our L{_WrappingProtocol} should be an L{IFileDescriptorReceiver} if the
        wrapped protocol is.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_endpoints.py