Book Image

UI Testing with Puppeteer

By : Dario Kondratiuk
Book Image

UI Testing with Puppeteer

By: Dario Kondratiuk

Overview of this book

Puppeteer is an open source web automation library created by Google to perform tasks such as end-to-end testing, performance monitoring, and task automation with ease. Using real-world use cases, this book will take you on a pragmatic journey, helping you to learn Puppeteer and implement best practices to take your automation code to the next level! Starting with an introduction to headless browsers, this book will take you through the foundations of browser automation, showing you how far you can get using Puppeteer to automate Google Chrome and Mozilla Firefox. You’ll then learn the basics of end-to-end testing and understand how to create reliable tests. You’ll also get to grips with finding elements using CSS selectors and XPath expressions. As you progress through the chapters, the focus shifts to more advanced browser automation topics such as executing JavaScript code inside the browser. You’ll learn various use cases of Puppeteer, such as mobile devices or network speed testing, gauging your site’s performance, and using Puppeteer as a web scraping tool. By the end of this UI testing book, you’ll have learned how to make the most of Puppeteer’s API and be able to apply it in your real-world projects.
Table of Contents (12 chapters)

Waiting for page events

Events are messages that a class sends when something happens. As a consumer, you can attach a function to those events, so you can listen to those events and react accordingly. You can find the code examples of these demos in the page-event-demos.js file inside the Chapter5 directory. To run that demo, you just need to run node page-event-demos.js.

This is how you could listen to responses without the waitForResponse:

page.on('response', response => 
  console.log('Response URL: ' + response.url()));
await page.goto('https://www.packtpub.com/');

In the first line, we say that we want to listen to the response event, and when a new response arrives, we want to print the URL in the console. Then, we call the goto function, and all the responses will start being written in the console.

Using the arrow (=>) is a simple way to write single-line functions. But, if you open a bracket, you can write more complex...