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)

Analyzing code coverage

In this last section, we will see how we can get code coverage using the Coverage class from Puppeteer. Code coverage is a metric that can be applied to any piece of code. To get the code coverage of a piece of code, you need some kind of tool to trace which lines of code are being executed, execute that code, and get the tracing result. It's like the performance tracing, but instead of measuring time, it measures executed lines of code.

You can see the code coverage on a page on Chrome using the Coverage tab. I didn't have that tab by default, so I needed to add it using the More tools option, as in the following screenshot:

Coverage tab

The Coverage tab works like the Performance tab. You need to start the tracing, run the page, or perform an action, then stop the tracing to get the results.

The result will be something like what we see in the preceding screenshot: A list of resources with the total bytes of that resources...