'A L{ConnectionRefusedError} exception is raised when a connection
attempt is actively refused by the other end.
Note: This test assumes no one is listening on port 80 UDP.'

def test_connectionRefused(self):

    client = GoodClient()
    clientStarted = client.startedDeferred = defer.Deferred()
    port = reactor.listenUDP(0, client, interface='127.0.0.1')
    server = Server()
    serverStarted = server.startedDeferred = defer.Deferred()
    port2 = reactor.listenUDP(0, server, interface='127.0.0.1')
    d = defer.DeferredList([clientStarted, serverStarted], fireOnOneErrback=True)
    def cbStarted(ignored):
        connectionRefused = client.startedDeferred = defer.Deferred()
        client.transport.connect('127.0.0.1', 80)
        for i in range(10):
            client.transport.write(intToBytes(i))
            server.transport.write(intToBytes(i), ('127.0.0.1', 80))
        return self.assertFailure(connectionRefused, error.ConnectionRefusedError)
    d.addCallback(cbStarted)
    def cbFinished(ignored):
        return defer.DeferredList([defer.maybeDeferred(port.stopListening), defer.maybeDeferred(port2.stopListening)], fireOnOneErrback=True)
    d.addCallback(cbFinished)
    return d
