def test_multiFileDescriptorReceivedPerRecvmsgTwoCMSGs(self):
        """
        _SendmsgMixin handles multiple file descriptors per recvmsg, calling
        L{IFileDescriptorReceiver.fileDescriptorReceived} once per received
        file descriptor. Scenario: two CMSGs with one FD each.
        """
        from twisted.python.sendmsg import SCM_RIGHTS

        def ancillaryPacker(fdsToSend):
            ancillary = [
                (SOL_SOCKET, SCM_RIGHTS, pack('i', fd))
                for fd in fdsToSend
            ]
            expectedCount = 2
            return ancillary, expectedCount

        self._sendmsgMixinFileDescriptorReceivedDriver(ancillaryPacker)

        _SendmsgMixin handles multiple file descriptors per recvmsg, calling
        L{IFileDescriptorReceiver.fileDescriptorReceived} once per received
        file descriptor. Scenario: two CMSGs with one FD each.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_unix.py