'It is safe and a no-op to call L{TuntapPort.stopListening} more than
once with no intervening L{TuntapPort.startListening} call.'

def test_multipleStopListening(self):

    self.port.startListening()
    self.port.stopListening()
    second = self.port.stopListening()
    self.reactor.advance(0)
    self.assertIsNone(self.successResultOf(second))
