NodeJS - Testing express application with supertest and mocha

Install dependencies.

npm init
npm install express --save
npm install mocha --save-dev # this will install mocha as developer dependencies.
npm install supertest --save-dev # this will supertest mocha as developer dependencies.

Here is the sample file to be tested.

// server.js
const express = require('express');
var app = express();

app.get('/', (req, res) => {
    res.send('Hello World!');

app.listen(3000); = app; // exporting app so that it can be easily accessible from test classes.

Here is the file for sample code having test case.

// server.test.js
const request = require('supertest');

var app = require('./server').app;

it('should return hello world response', (done) => {
        .expect('Hello World!')