def test_blockingRead(self):
        """
        Blocking reads are not implemented by L{Tunnel.read}.  Attempting one
        results in L{NotImplementedError} being raised.
        """
        tunnel = Tunnel(MemoryIOSystem(), os.O_RDONLY, None)
        self.assertRaises(
            NotImplementedError, tunnel.read, 1024)

        Blocking reads are not implemented by L{Tunnel.read}.  Attempting one
        results in L{NotImplementedError} being raised.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/pair/test/test_tuntap.py