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 elements

Before acting on an element, you need to make sure of two things: first, that the element is there, it exists in the DOM; and second, you can act on that element. In other words, it's visible to the user. Let's see how we can wait for our element to be ready.

You should wait for a selector after some kind of network call. You goto a page, wait for a selector, and then you act. You click on a button, wait for a selector, and then you act.

In some cases, the selector you need to wait for is easy to find. On our login page, we need to wait for the user name input. In other cases, such as our home page, we would need to wait for the div element containing all the products. It's just a little bit more complicated but still straightforward.

But what if we want to test Mango's newsletter popup? Maybe the pop-up HTML is on the page, but it's not visible. Here's where I start to consider waiting as a kind of art. It's not just...