Automated Unit Tests for node.js

This repository includes basic unit testing logic for automated tests for example REST node backend.

Which test tools are used

Mocha: JS test framework used for running tests
Chai: used to validate test outcome, test-driven development (TDD) assertion library for NodeJS
Sinon: managing side effects & external depencies

Configuration

Add tests to ./test folder
edit test script in package.json e.g. mocha --timeout 5000
Run tests npm run test

How to write tests

Syntax in tests define the test structure

describe("my group title")
it("my test name")

const expect = require('chai').expect;

describe("auth middleware) {

    it('should be 2', function() {
        const num1 = 1;
        const num2 = 1;
        expect(num1 + num2).to.equal(2);
    })
    // ... other tests
}

Using Sinon to simulate stubs

You can overwrite jwt function to mock the functionality or another (better) option is to use "sinon" to simulate stub functions. You can "restore" function back to normal once you don't need custom functionality anymore.

it("should yield a userId after decoding the token", function() {
    const req = {
      get: function(headerName) {
        return "Bearer djfkalsdjfaslfjdlas";
      }
    };

    // mock verify function with sinon
    sinon.stub(jwt, "verify");
    jwt.verify.returns({ userId: "abc" });

    authMiddleware(req, {}, () => {});
    expect(req).to.have.property("userId");
    expect(req).to.have.property("userId", "abc");
    expect(jwt.verify.called).to.be.true;

    // restore original function
    jwt.verify.restore();
  });

Testing controllers

Test if parameters are invalid
Mock database operations
Use hooks before(), beforeEach, after(), afterEach() to avoid unnecessary code duplication
Hooks: prepare tests by initializing mongoose connection before tests are run by using before() lifecycle hook so that you have to connect to db only once
It is a good idea to setup a dedicated database for testing, do NOT use production database for this

const expect = require("chai").expect;
const sinon = require("sinon");
const mongoose = require("mongoose");
const User = require("../models/user");
const AuthController = require("../controllers/auth");

describe("Auth Controller", function() {

  before(function(done) {
    mongoose
      .connect(process.env.MONGODB_TEST_URI)
      .then(result => {
        const user = new User({
          email: "test@test.com",
          password: "tester",
          name: "Test",
          posts: [],
          _id: "5c0f66b979af55031b34728a"
        });
        return user.save();
      })
      .then(() => {
        done();
      });
  });

  // note that database operation is asynchronous
  // to tell this to mocha, add "done" as a parameter
  // call done() inside block where async code is finished
  it("should throw an error with code 500 if accessing the database fails", function(done) {
    // simulate findOne mongoose method using Sinon
    sinon.stub(User, "findOne");
    User.findOne.throws();

    // mock req object
    const req = {
      body: {
        email: "test@test.com",
        password: "tester"
      }
    };

    // use actual controller to test it agains mock data and sinon

    AuthController.login(req, {}, () => {}).then(result => {
      expect(result).to.be.an("error");
      expect(result).to.have.property("statusCode", 500);
      done();
    });

    User.findOne.restore();
  });

  ...

Links

Mocha documentation Chai documentation Sinon documentation

Zuzze / node-unit-testing