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)

Introduction to HTML, the DOM, and CSS

You won't be able to find elements if you don't know CSS, and you won't understand CSS if you don't understand the DOM and HTML. So, we need to start with the basics.

I bet you've heard that you can build a site with HTML, CSS, and JavaScript. You might be using different server-side technologies. Your frontend might be implemented using cool technologies such as React or Angular. But in the end, the result will be a page based on HTML, CSS, and JavaScript.

HTML is the page's content. If you go to any website, open the DevTools, and click on the Elements tab, you will see the content of the page. You will see the page's title. If it's a news site, you will see all the articles there. If you visit a blog post, you will see the text of that post.

Without CSS, an HTML page would look like text written in Notepad. CSS not only brings color and fonts, but it's also the scaffolding that gives structure...