def _stopsReadingTest(self, style):
        """
        Test that L{TuntapPort.doRead} has no side-effects under a certain
        exception condition.

        @param style: An exception instance to arrange for the (python wrapper
            around the) underlying platform I{read} call to fail with.

        @raise C{self.failureException}: If there are any observable
            side-effects.
        """
        self.port.startListening()
        tunnel = self.system.getTunnel(self.port)
        tunnel.nonBlockingExceptionStyle = style
        self.port.doRead()
        self.assertEqual([], self.protocol.received)

        Test that L{TuntapPort.doRead} has no side-effects under a certain
        exception condition.

        @param style: An exception instance to arrange for the (python wrapper
            around the) underlying platform I{read} call to fail with.

        @raise C{self.failureException}: If there are any observable
            side-effects.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/pair/test/test_tuntap.py