'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.'

def _stopsReadingTest(self, style):

    self.port.startListening()
    tunnel = self.system.getTunnel(self.port)
    tunnel.nonBlockingExceptionStyle = style
    self.port.doRead()
    self.assertEqual([], self.protocol.received)
