evented it tests (working)

var dgram = require('dgram');

var client_address = "0.0.0.0"
var client_port = 9002;

var server_address = "0.0.0.0"
var server_port = 9001

var maxWaitTimeForResponse = 6000;

server_socket = dgram.createSocket('udp4');
server_socket.on('listening', function() { console.log("Server is listening"); });
server_socket.bind(server_port);

function sendMessageServerToClient(message){
    var pBuf = new Buffer(message);
    server_socket.send(pBuf, 0, pBuf.length, client_port, client_address, function(err, bytes) { if(err){ throw err } });
}

server_socket.on('message', function(msg, rinfo) {

    //acknowledge reciept of message
    sendMessageServerToClient("Message Received");

    /*
        Do lots more work
    */

    //sent client some more messages after the work has completed
    setTimeout(
        function(){
            sendMessageServerToClient("More results from your request");
        },
        3000
    )

});

client_socket = dgram.createSocket('udp4');
client_socket.on('listening', function() { console.log("Client is listening"); });
client_socket.bind(client_port);


var responseReceivedDone;
function registerResponseExpected(){
    describe("Wait for response from server", function(){
        this.timeout(maxWaitTimeForResponse);
        it("should register a callback for message receipt", function(done){
            responseReceivedDone = done;
        });
    });
}


function sendMessageClientToServer(message, callback){
    var pBuf = new Buffer(message);
    registerResponseExpected();
    client_socket.send(pBuf, 0, pBuf.length, server_port, server_address, function(err, bytes) {
        callback();
    });
}

var handleMessageFromServer;
client_socket.on('message', function(msg, rinfo){
    responseReceivedDone();
    handleMessageFromServer(msg);
});

//conduct a test
describe("Conversation with server without big timeout", function(){

    var step1 = function(msg){
        describe("Validate an ack from server", function(){

            registerResponseExpected();
            handleMessageFromServer = step2;

            it("should contain 'Message Received'", function(done){
                if(msg.toString()!="Message Received"){
                    done(new Error("Client didn't receive correct ack message. I got " + msg.toString()));
                }else{
                    done();
                }
            });

        });
    }

    var step2 = function(msg){
        describe("Validate additional response from server", function(){

            handleMessageFromServer = null;

            it("should contain 'More results from your request'", function(done){
                if(msg.toString()!="More results from your request"){
                    done(new Error("Client didn't receive correct results message. I got " + msg.toString()));
                }else{
                    done();
                }

            })

        })
    }

    handleMessageFromServer = step1;

    it("should send message to server", function(done){
        sendMessageClientToServer("Hello", function(err){
            done(err)
        });
    })

})