End To End Testing With Puppeteer - A Comprehensive Guide

Over the years, the focus of the development agencies has shifted from evolution to improved user experience and sustainability. Besides, the innovation that led to the introduction of automation testing to already existing manual landscape further caused the flooding of market with so many unique automation testing tools.  

Though there are so many tools made to simplify test automation solutions, automated testing with Puppeteer is gaining significant recognition. In this blog, we will dive through every detail of understanding Puppeteer, right from its features and installation to best practices and more.  

What Is Puppeteer? 

Puppeteer is a powerful Node.js library developed by Google that provides a high-level API for automating and controlling headless and Chrome or Chromium based browsers. From UI testing with Puppeteer to testing the functionalities, interacting with web pages, performing various actions like clicking buttons, filling forms, taking screenshots, and extracting data from websites programmatically, are some common puppeteer test examples. 

Also, Puppeteer's headless mode is particularly valuable for running automated tests and scraping data without the need for a visible browser window, making it efficient and suitable for server-side applications. 

Since Puppeteer automation framework provides a simple and expressive API, it has become a popular choice for web developers and testers to automate tasks and create robust web automation solutions. It's worth noting that while Puppeteer is designed for Google Chrome, it can also work with other Chromium-based browsers like Microsoft Edge. 

Installing Puppeteer 

To install Puppeteer for testing, you'll need to follow these steps: 

Prerequisites 

   - Make sure you have Node.js installed on your computer. You can download it from the official Node.js website: https://nodejs.org/ 

Initialize a Node.js project 

   - Create a new folder for your project (if you haven't already) and open a terminal or command prompt in that folder. 

   - Run the following command to initialize a new Node.js project and create a `package.json` file: 

     ``` 

     npm init -y 

     ``` 

Install Puppeteer 

   - Now, you can install Puppeteer by running the following command in your terminal or command prompt: 

     ``` 

     npm install puppeteer 

     ``` 

Check Puppeteer Version (optional) 

   - To ensure that Puppeteer was installed successfully, you can check its version using the following command: 

     ``` 

     npx puppeteer --version 

     ``` 

Run a Test (optional) 

   - To check if Puppeteer is working correctly, you can run a simple test. Create a new JavaScript file (e.g., `test.js`) in your project folder and add the following code: 

     ```javascript 

     const puppeteer = require('puppeteer'); 

     (async () => { 

       const browser = await puppeteer.launch(); 

       const page = await browser.newPage(); 

       await page.goto('https://www.example.com'); 

       await page.screenshot({ path: 'example.png' }); 

       await browser.close(); 

     })(); 

     ``` 

   - Replace `'https://www.example.com'` with the URL of the website you want to test. 

   - Save the file and run it using Node.js: 

     ``` 

     node test.js 

     ``` 

   - This script will launch a headless browser, open the specified URL, take a screenshot, and save it as `example.png` in your project folder. 

That's it! You have successfully installed Puppeteer and have run a simple test. Now, you can now easily use Puppeteer testing framework for more advanced web testing and automation tasks. Make sure to refer to Puppeteer's official documentation for detailed usage and examples: https://pptr.dev/

Why Puppeteer For Software Testing? 

Puppeteer's simplicity, versatility, and powerful features make it a popular choice for software testing, web scraping, and automation tasks in the modern web development landscape. Besides, Puppeteer is a popular choice amongst QA engineers engaged in software testing for many other reasons. Some of these could be listed as: 

• Headless Browser Automation: Puppeteer allows you to control a headless version of the Chromium browser, which means there's no visible UI when running tests. This headless mode enables faster test execution and makes it suitable for server-side and continuous integration testing. 

• Easy to Use: Puppeteer provides a straightforward and user-friendly API, making it accessible even to developers with limited experience in automated testing. The API is well-documented and has a thriving community, which makes troubleshooting and learning much easier. 

• Full-Page Screenshots and PDF Generation: Puppeteer can capture full-page screenshots and generate PDFs of web pages. This functionality is beneficial for visual regression testing, where you can compare screenshots of different versions of a webpage to identify any unintended changes in the UI. 

• Real User Scenarios: Puppeteer allows you to simulate user interactions on a web page, such as clicking buttons, filling out forms, and navigating between pages. This capability enables you to test real user scenarios and ensure that critical functionalities work as expected. 

• Web Scraping and Data Extraction: Apart from testing, Puppeteer can also be used for web scraping and data extraction tasks. This makes it a versatile tool that can serve multiple purposes within a development workflow. 

• Integration with Testing Frameworks: Puppeteer can be integrated with popular testing frameworks like Jest, Mocha, and others. This allows you to write and manage tests using familiar testing tools and methodologies. 

• Cross-Browser Testing: Although Puppeteer primarily controls Chromium, it can be combined with services like BrowserStack or Sauce Labs to perform cross-browser testing on various browsers and platforms. 

• Performance Testing: Puppeteer can be used to analyze and measure web page performance metrics. You can track metrics such as load times, resource utilization, and rendering speed, helping you optimize the performance of your web applications. 

• Automated Tasks: Puppeteer can be utilized for automating repetitive tasks on the web, such as form filling, data extraction, or generating reports. This can save significant time and effort for developers and testers. 

Explore the idea of ultimate test automation in modern day enterprise 

Read the blog: Enterprise Test Automation: Breaking The Barriers 

Testing With Puppeteer Best Practices 

Testing with Puppeteer can be an efficient way to automate browser testing. Here are some best practices to consider when testing with Puppeteer: 

• Use Headless Mode 

Puppeteer can run in headless mode (without a visible browser window). It is generally recommended to use headless mode for most of your tests as it's faster and consumes fewer resources. 

```javascript 

const puppeteer = require('puppeteer'); 

(async () => { 

  const browser = await puppeteer.launch({ headless: true }); 

  const page = await browser.newPage(); 

  // Your test code here 

  await browser.close(); 

})(); 

``` 

• Wait for Network Requests to Complete 

When interacting with web pages, network requests may take some time to complete. Always use proper waiting techniques to ensure that the page is fully loaded before performing actions or assertions. 

```javascript 

await page.goto('https://example.com'); 

await page.waitForNavigation(); // Wait for full page load 

``` 

• Use Selectors Wisely 

Instead of relying on XPath, try to use CSS selectors or more specific identifiers like `data-testid` for better code readability and maintenance. 

```javascript 

await page.click('#submit-button'); // Using CSS selector 

await page.click('[data-testid="submit-button"]'); // Using data-testid attribute 

``` 

• Isolate Tests and Avoid Shared State 

Each test should be independent and not rely on the state of other tests. Isolating tests will make them more predictable and easier to debug. 

• Use Page Emulation 

Puppeteer allows you to emulate different devices and screen sizes. This is particularly useful for responsive web testing.  

```javascript 

await page.setViewport({ width: 1280, height: 720 }); 

``` 

• Mock Network Requests when Needed 

In some cases, it's beneficial to mock network requests to simulate specific scenarios and avoid external dependencies during testing. 

• Handle Errors Gracefully 

Make sure to handle errors properly in your tests to prevent the entire test suite from failing if one test encounters an issue. 

• Use Headless Testing for Continuous Integration 

When integrating Puppeteer tests into your CI/CD pipeline, running tests in headless mode is a good practice to avoid any dependencies on graphical interfaces. 

Dive into learning how Continuous Integration works and complements QA 

Read here: Explaining the Process of Continuous Integration & Continuous Testing 

• Avoid Unnecessary User Interactions 

Puppeteer allows you to interact with pages as if a real user is doing so, but try to minimize unnecessary user interactions to improve the efficiency and stability of your tests. 

• Monitor Performance Metrics 

Puppeteer can collect performance metrics from the browser, which can help you identify potential performance bottlenecks in your application. 

```javascript 

const performance = await page.evaluate(() => JSON.stringify(window.performance)); 

console.log(JSON.parse(performance)); 

``` 

• Clean Up Resources 

Always close the browser instance after the test is complete to release resources properly. 

```javascript 

const browser = await puppeteer.launch(); 

// Your test code here 

await browser.close(); 

``` 

By following these best practices, you can create more reliable and maintainable Puppeteer tests for your web applications.  

Happy Testing! 

Need help implementing Puppeteer for your next big project? Looking to outsource QA services and collaborate with a team that holds proficiency working with Puppeteer and all the advanced tool stack? End your search with BugRaptors’ ISTQB certified professionals that are always ready to lend a helping hand.  

For any queries or information, contact us today.