'If a UDP datagram is written the tunnel device then it is received by
the network to which it is addressed.'

def test_send(self):

    key = randrange((2 ** 64))
    message = ('hello    world:' + intToBytes(key))
    self.addCleanup(socket.setdefaulttimeout, socket.getdefaulttimeout())
    socket.setdefaulttimeout(120)
    port = self.system.receiveUDP(self.fileno, self._TUNNEL_LOCAL, 12345)
    packet = self.helper.encapsulate(50000, 12345, message)
    self.system.write(self.fileno, packet)
    packet = port.recv(1024)
    self.assertEqual(message, packet)
