'L{IReactorUNIXDatagram.listenUNIXDatagram} raises
L{error.CannotListenError} if the unix socket specified is already in
use.'

def test_cannotListen(self):

    addr = self.mktemp()
    p = ServerProto()
    s = reactor.listenUNIXDatagram(addr, p)
    self.assertRaises(error.CannotListenError, reactor.listenUNIXDatagram, addr, p)
    s.stopListening()
    os.unlink(addr)
