test.js

var http = require('http'),
    should = require('should'),
    io = require('socket.io'),
    decode = require('.npm/socket.io/0.6.8/package/lib/socket.io/utils').decode,
    encode = require('.npm/socket.io/0.6.8/package/lib/socket.io/utils').encode,
    WebSocket = require('.npm/socket.io/0.6.8/package/support/node-websocket-client/lib/websocket.js').WebSocket;

exports['Socket.IO mocking'] = function(assert){
    var _server = require('http').createServer(function(){});
    // A mock client object.
    var _client;
    // Used as an easy way to know when to shut the server down.
    var messages_to_receive = 4;

    var port = 5000 // Any number will do
    _server.listen(port, function(){
        // When this function is called, the server will be started.
        // We can now write some mocked-out client code to connect to it.

        // This is the equivalent to "new io.Socket(...)" in the browser
        // What we send here will be received in the server as if it were sent from a browser
        _client = new WebSocket('ws://localhost:' + port + '/socket.io/websocket', 'borf');
        _client.messages = [];

        // The encode/decode parts are not obvious - do not forget them :) :)

        _client.onmessage = function(ev) {
            // These are the messages received at the "client"
            this.messages.push(decode(ev.data)[0])
            if (--messages_to_receive == 0)
                close();
        };

        // This part is optional
        _client.onopen = function(){
            _client.send(encode('Test Message'));
        };

    });

    // Init the server-side socket as we always do.
    // This is the same kind of code as in the chat tutorial.
    // In here you can put your actual Socket.IO handler on the server
    // (which we will be testing).
    var _socket = io.listen(_server);
    _socket.on('connection', function(conn){
        conn.on('message', function(msg){
            msg.should.equal('Test Message');
            if (--messages_to_receive == 0)
                close();
            // This part is optional
            conn.send('From server');
        })

        // This part is optional
        _socket.broadcast("Broadcast message");
    });

    var close = function() {
        _client.messages.length.should.equal(3);
        // _client.messages[0] is always the sessionId of the client.
        _client.messages[1].should.equal("Broadcast message");
        _client.messages[2].should.equal("From server");
        _client.close();
        _server.close();
    }
}