How to test node.js websocket server?

Question

I am using sockjs with a standard configuration.

var ws = sockjs.createServer(); ws.on('connection', function(conn) { conn.on('data', function(message) { wsParser.parse(conn, message) }); conn.on('close', function() { }); }); var server = http.createServer(app); ws.installHandlers(server, {prefix:'/ws'}); server.listen(config.server.port, config.server.host); 

Function

wsParser.parse works as follows:

 function(conn, message) { (...) switch(message.action) { case "titleAutocomplete": titleAutocomplete(conn, message.data); break; (...) // a lot more of these } 

Each method called on the switch sends a message back to the client.

 var titleAutocomplete = function(conn, data) { redis.hgetall("titles:"+data.query, function(err, titles){ if(err) ERR(err); if(titles) { var response = JSON.stringify({"action": "titleAutocomplete", "data": {"titles": titles}}); conn.write(response); } }) }; 

Now my problem is that I would like to do tests for my code (better late than I guess), and I have no idea how to do this. I started writing regular http tests using mocha + supertest, but I just don't know how to handle websockets.

I would like to have only one network connection to reuse all tests, I bind the websocket connection to the user session after the first message, and I want to check this persistence as well.

How can I use the ws client onmessage event and use it in my tests? How can tests tell you about all messages received and find out which one they should wait for?

Answer 1

Collegue at work asked if it really should be a client connection or just mock it. It turned out that this was the way to go. I wrote a small helper class wsMockjs

 var wsParser = require("../wsParser.js"); exports.createConnectionMock = function(id) { return { id: id, cb: null, write: function(message) { this.cb(message); }, send: function(action, data, cb) { this.cb = cb; var obj = { action: action, data: data } var message = JSON.stringify(obj); wsParser.parse(this, message); }, sendRaw: function(message, cb) { this.cb = cb; wsParser.parse(this, message); } } } 

Now in my mocha test I'm just doing

 var wsMock = require("./wsMock.js"); ws = wsMock.createConnectionMock("12345-67890-abcde-fghi-jklmn-opqrs-tuvwxyz"); (...) describe('Websocket server', function () { it('should set sessionId variable after handshake', function (done) { ws.send('handshake', {token: data.token}, function (res) { var msg = JSON.parse(res); msg.action.should.equal('handshake'); msg.data.should.be.empty; ws.should.have.property('sessionId'); ws.should.not.have.property('session'); done(); }) }) it('should not return error when making request after handshake', function (done) { ws.send('titleAutocomplete', {query: "ter"}, function (res) { var msg = JSON.parse(res); msg.action.should.equal('titleAutocomplete'); msg.data.should.be.an.Object; ws.should.have.property('session'); done(); }) }) }) 

It works like a charm and saves connection status and variables between requests.