Unit test your Nodejs RESTful API using mocha

Its always a good idea to have some quick and simple automated tests in place for your REST api so that you know that you didnt break anything that already worked when you add more functionality. Fortunately, setting up automated tests is not that hard in nodejs. You just gotta know the right libraries to use and how they work together. And thats exactly what we will set out to achieve in this article. All the source code for this tutorial is combined with the node starter kit project and can be found on github in the branch rest-api-unit-test This is what you would be able to do by the time we are done with this article. Run an npm script executes mocha tests against your nodejs RESTful api. Lets jump in.

Background

module.exports = function(app, settings){

    var url = require('url'),
        express = require('express'),
        usersRouter = express.Router();

    var users  = [
        {
            name: 'Tim Cook'
        },
        {
            name: 'Jony Ive'
        },
        {
            name: 'Steve Jobs'
        },
    ];

    // Get a list of all the users
    usersRouter.get('/', function(req, res, next){
        res.json(users);
    });

    // Get the user at the index
    usersRouter.get('/:index', function(req, res, next){
        res.json(users[req.params.index]);
    });

    // Create a new user
    usersRouter.post('/', function(req, res, next){
        users.push(req.body);
        res.json(users[users.length - 1]);
    });

    app.use('/api/users', usersRouter);

};

Packages

1. mocha : The testing framework we will use.
2. grunt-mocha-test : The task runner to help us setup mocha.
3. chai : The assertion library that we will use within our mocha tests.
4. supertest : A library that lets you fake requests to test your REST api's.

npm install mocha grunt-mocha-test chai supertest --save-dev

Configuration

scripts:{
    // other scripts
    // ...
    "tests-unit": "grunt mochaTest"
}

module.exports = function(grunt) {

    grunt.initConfig({
        pkg: grunt.file.readJSON('package.json')
    });

    grunt.config( 'mochaTest', require('./grunt/mochaTest.js') );

    grunt.loadNpmTasks('grunt-mocha-test');
}

module.exports = {
  all: {
    options: {
      reporter: 'list'
    },
    src: ['tests/unit/**/*.test.js']
  }
};

The Test

var request = require('supertest'),
    expect = require("chai").expect;

var express = require('express'),
    ROOT_DIR = __dirname + '/../..',
    config = require(ROOT_DIR + '/config'),
    bodyParser = require('body-parser'),
    methodOverride = require('method-override'),
    cookieParser = require('cookie-parser'),
    session = require('express-session'),
    app = express();

var settings = {
        config: config
    };

// all environments
app.use(bodyParser.urlencoded({
    extended: true
}));
app.use(bodyParser.json());
app.use(methodOverride());
app.use(cookieParser());
app.use(session({
    secret: config.SESSION_SECRET ,
    saveUninitialized: true,
    resave: true
}));

//This allows you to require files relative to the root in any file
requireFromRoot = (function(root) {
    return function(resource) {
        return require(root+"/"+resource);
    }
})(ROOT_DIR);

• We save a reference to the console.log. We do this because in my routes, I print logging statements to the console which will ruin the format of my mocha tests. So we save a reference to the log object and before each test executes, we will set it to an empty function(in the beforeEach function which runs before each 'it' block).
• In the before function(which runs once at the beginning of the describe block) we require the route we intend to test in the test cases of this describe block.
• In each test case, when we are ready to use our assertions, we again reference the console.log to the previously saved log variable.

describe('#/api/users', function(){

    var log = console.log;

    before(function(done){
        require(ROOT_DIR + '/routes/users')(app, settings);
        done();
    });

    beforeEach(function(){

        // Done to prevent any server side console logs from the routes
    // to appear on the console when running tests
        console.log=function(){};

    });

  it('- should GET users', function(done){
    request(app)
      .get('/api/users')
      .end(function(err, res){
        // Enable the console log to print the assertion output
        console.log = log;
        var data = JSON.parse(res.text);
        expect(err).to.be.null;
                expect(data.length).to.equal(3);
        done();
      });
  });

  it('- should GET a user at index (1)', function(done){
    request(app)
      .get('/api/users/1')
      .end(function(err, res){
        // Enable the console log
        console.log = log;
        var data = JSON.parse(res.text);
        expect(err).to.be.null;
                expect(data.name).to.equal('Jony Ive');
        done();
      });
  });

  it('- should POST a user and get back a response', function(done){
    var user = {
        name: 'Steve Wozniak'
    };

    request(app)
      .post('/api/users')
      .send(user)
      .end(function(err, res){
        // Enable the console log
        console.log = log;
        var data = JSON.parse(res.text);
        expect(err).to.be.null;
        expect(data.name).to.equal(user.name);
        done();
      });
  });

});

Also Read:

1. Debugging nodejs applications using node-inspector and Chrome Dev Tools
2. Installing, Listing and Uninstalling packages using npm
3. What does npm start do in nodejs
4. Testing promise sequence using mocha, chai, chai-as-promised, sinon