Test a Node RESTful API with Mocha and Chai

In this article we will see, how we will test our rest API via mocha and chai, I am assuming that you know the mocha and chai, if you still need then I am providing the link.

Mocha — Mocha is a feature-rich JavaScript test framework running on Node.js and in the browser, making asynchronous testing simple and fun

Chai — Chai is a BDD / TDD assertion library for node and the browser that can be delightfully paired with any javascript testing framework.

Prerequisites

1. First, we need a basic node js project with one basic API.
2. Some dev dependencies, which are given below.

    "chai": "^4.3.7",
    "chai-http": "^4.3.0",
    "mocha": "^10.2.0",
    "mochawesome": "^7.1.3",
    "sinon": "^15.0.1",

Kindly follow these steps.

Step 1:- First will set up the folder for the unit test cases which will be the unit-test, as you can see in the given structure.

folder structure

Inside unit-test we can manage both mock data and test cases based on our project structure.

Step 2:- Now time to set up the script inside the package.json file like this.

    "unit-test": "mocha 'unit-test/test-cases/**/*.spec.js'",

Step 3:- Will write one route for the unit test case, if you don't have any route/api.

Route

// Load required modules
const express = require('express');
const cloudAgent = require('../controllers/cloud');

// Default settings
const router = express.Router();

// Routes list for cloud_agent
router.get('/health', cloudAgent.health);

module.exports = router;

Controller

'use strict';

//load required modules
//const msg = require('../utils/lang/messages');
//const logger = require('../utils/log');

//api for health checkup
exports.health = async (req, res) => {
 console.log('Service Healthy');
 res.send({
  code: "200",
  message: "Service Healthy",
 });
}

Curl for this API

curl --location --request GET 'http://localhost:3001/health'

Response for API

{
    "code": "200",
    "message": "Service Healthy"
}

Step 4:- Will write the test case for the above route/api.

save this file inside the unit-test folder.

'use strict';

const chai = require('chai');    // for assert
let chaiHttp = require('chai-http');
const expect = chai.expect;      // type of assert
const sinon = require("sinon");  // function mocking
chai.use(chaiHttp);

// Load configurations
const config = require('../../../config/cloud_agent');
const server = require('../../../app');

/* Sample test case */
describe('Sample test-case', () => {
    it("Sample test case for the project", async function () {
        this.timeout(3000);
        return expect("data").to.be.a('string');
    });

    // Run hook after each and every tets-case
    afterEach(function () {
        sinon.restore(); // Unwraps the spy
    });
});

/* Health api test case */
describe("/health", () => {
    it("Health api test case", async function () {
        this.timeout(3000);
        try {
            let res = await chai.request('http://localhost:3001').get(config.unit_testing.api.health);
            expect(res).have.status(200);
            expect(res.body).to.be.a('object');
            return;
        } catch (error) {
            throw (new Error(error));
        }
    });

    // Run hook after each and every tets-case
    afterEach(function () {
        sinon.restore(); // Unwraps the spy
    });
});

Step 5:- Now, time to run the test cases.

Will run the complete test case which all are inside the test-case/test-cases folder via the given command.

npm run unit-test

And it will look like this.

Sample output

That’s it for this time! I hope you enjoyed this post. As always, I welcome questions, notes, comments and requests for posts on topics you’d like to read. See you next time! Happy Coding !!!!!