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 network calls

In Chapter 3, Navigating through a website, we talked about requests and responses. Every page navigation begins with a request to a page. The server then processes that request and sends a response. That response generally is an HTML page, which has resources declared that need to be requested. The server will process each of those requests again and send many responses.

But that's not all. Modern apps will send requests to the server based on user actions. Take Google Maps: the user moves the mouse, and the page will need to request a new picture of the map without reloading the entire page.

We don't work on the Google Maps teams, but many users have reported that the home page sometimes doesn't load the product image after login. So, we could write a test to check that it should load an image. Oh… you thought we were going to test Google Maps? Not this time, sorry.

In this case, we can use waitForResponse(urlOrPredicate, ...