How To Write End-to-End Tests in Node.js Using Puppeteer and Jest

End-to-end testing is essential for ensuring that all components of your application work together as expected. Puppeteer is a Node library that provides a high-level API over the Chrome DevTools Protocol, allowing you to control Chrome or Chromium programmatically. Jest is a popular testing framework for JavaScript and Node.js applications. Here's how to write end-to-end tests in Node.js using Puppeteer and Jest:

1. Install Dependencies:

   First, you need to install Puppeteer and Jest:

                   
                       npm install puppeteer jest --save-dev
                   
               

2. Set Up Jest Configuration:

   Create a jest.config.js file in your project's root directory and configure Jest to use Puppeteer:

                   
                       module.exports = {
                           testEnvironment: 'node',
                           setupFilesAfterEnv: ['./jest.setup.js']
                         };                      
                   
               

3. Set Up Jest Setup File:

   Create a jest.setup.js file in your project's root directory to initialize Puppeteer:

                   
                       const { setup: setupPuppeteer } = require('jest-environment-puppeteer');
   
                       module.exports = async function globalSetup(globalConfig) {
                         await setupPuppeteer(globalConfig);
                       };                    
                   
               

4. Write Your Tests:

   Create your test files, for example, example.test.js, and write your end-to-end tests using Puppeteer:

                   
                       const { chromium } = require('playwright');
   
                       describe('Example E2E Tests', () => {
                         let browser;
                         let page;
                       
                         beforeAll(async () => {
                           browser = await chromium.launch();
                           page = await browser.newPage();
                         });
                       
                         afterAll(async () => {
                           await browser.close();
                         });
                       
                         test('should display the title correctly', async () => {
                           await page.goto('https://example.com');
                           const title = await page.title();
                           expect(title).toBe('Example Domain');
                         });
                       
                         test('should have the correct content', async () => {
                           await page.goto('https://example.com');
                           const content = await page.$eval('p', (el) => el.textContent);
                           expect(content).toContain('This domain is for use in illustrative examples');
                         });
                       });                    
                   
               

5. Run Your Tests:

   You can run your tests using Jest:

                   
                       npx jest
                   
               

6. Review Test Results:

   Jest will execute your tests using Puppeteer and display the results in the terminal.

By following these steps, you can set up end-to-end tests for your Node.js application using Puppeteer and Jest. These tests allow you to automate browser interactions and verify that your application behaves correctly from a user's perspective. This approach helps catch bugs and regressions before they reach production, ensuring a smoother user experience.

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