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.

Conclusion:

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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