Node.js – How do i test the express app with mocha

expressmocha.jsnode.js

I've just added shouldjs and mocha to my express app for testing, but I'm wondering how to test my application. I would like to do it like this:

app = require '../app'
routes = require '../src/routes'

describe 'routes', ->
  describe '#show_create_user_screen', ->
    it 'should be a function', ->
      routes.show_create_user_screen.should.be.a.function
    it 'should return something cool', ->
      routes.show_create_user_screen().should.be.an.object

Of course, the last test in that test-suite just tells med that the res.render function (called within show_create_user_screen) is undefined, probably becouse the server is not running and the config has not been done. So I wonder how other people set up their tests?

Best Answer

found an alternative in connect.js tests suites

They are using supertest to test a connect app without binding the server to any port and without using mock-ups.

Here is an excerpt from connect's static middleware test suite (using mocha as the test runner and supertest for assertions)

var connect = require('connect');

var app = connect();
app.use(connect.static(staticDirPath));

describe('connect.static()', function(){
  it('should serve static files', function(done){
    app.request()
    .get('/todo.txt')
    .expect('contents', done);
  })
});

This works for express apps as well

Standard Method (no library)

The arguments are stored in process.argv

Here are the node docs on handling command line args:

process.argv is an array containing the command line arguments. The first element will be 'node', the second element will be the name of the JavaScript file. The next elements will be any additional command line arguments.

// print process.argv
process.argv.forEach(function (val, index, array) {
  console.log(index + ': ' + val);
});

This will generate:

$ node process-2.js one two=three four
0: node
1: /Users/mjr/work/node/process-2.js
2: one
3: two=three
4: four

Javascript – How to decide when to use Node.js

You did a great job of summarizing what's awesome about Node.js. My feeling is that Node.js is especially suited for applications where you'd like to maintain a persistent connection from the browser back to the server. Using a technique known as "long-polling", you can write an application that sends updates to the user in real time. Doing long polling on many of the web's giants, like Ruby on Rails or Django, would create immense load on the server, because each active client eats up one server process. This situation amounts to a tarpit attack. When you use something like Node.js, the server has no need of maintaining separate threads for each open connection.

This means you can create a browser-based chat application in Node.js that takes almost no system resources to serve a great many clients. Any time you want to do this sort of long-polling, Node.js is a great option.

It's worth mentioning that Ruby and Python both have tools to do this sort of thing (eventmachine and twisted, respectively), but that Node.js does it exceptionally well, and from the ground up. JavaScript is exceptionally well situated to a callback-based concurrency model, and it excels here. Also, being able to serialize and deserialize with JSON native to both the client and the server is pretty nifty.

I look forward to reading other answers here, this is a fantastic question.

It's worth pointing out that Node.js is also great for situations in which you'll be reusing a lot of code across the client/server gap. The Meteor framework makes this really easy, and a lot of folks are suggesting this might be the future of web development. I can say from experience that it's a whole lot of fun to write code in Meteor, and a big part of this is spending less time thinking about how you're going to restructure your data, so the code that runs in the browser can easily manipulate it and pass it back.

Here's an article on Pyramid and long-polling, which turns out to be very easy to set up with a little help from gevent: TicTacToe and Long Polling with Pyramid.

Best Answer

Related Solutions

Javascript – How to pass command line arguments to a Node.js program

Standard Method (no library)

Javascript – How to decide when to use Node.js

Related Topic