def test_noSuchDevice(self):
        """
        L{_IInputOutputSystem.open} raises L{OSError} when called with a
        non-existent device path.
        """
        system = self.createSystem()
        self.assertRaises(
            OSError,
            system.open, b"/dev/there-is-no-such-device-ever", os.O_RDWR)

        L{_IInputOutputSystem.open} raises L{OSError} when called with a
        non-existent device path.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/pair/test/test_tuntap.py