react-hooks-testing-library VS jsdom

While generally it's recommended to test the component using the hooks rather than the hooks themselves, sometimes you might find it necessary to test custom hooks directly. For such cases, there's React Hooks Testing Library. This library allows you to create a simple test harness for React hooks that handles running them within the body of a function component, as well as updating and unmounting them.

To do so, we can install and use Render hooks from React Testing Library:

Of course, you could isolate the logic inside a hook, and there's an awesome way of testing it with renderHook. But yet, you're trapped into react features, if they change their API, you will have to put your hands in your working logic and adapt some stuffs to keep up to date.

Relocating functions to a custom hook makes them accessible for testing (plus you’re keeping business logic separate from the UI, in accordance with best practices). There’s even a library to help with testing custom hooks: react-hooks-testing-library.

testing-library provides one more library exactly for such purpose allowing us to avoid headache and safe strength for actual testing. It is called @testing-library/react-hooks

Next, we need to install react-hooks-testing-library package. It's a simple testing utility that allows testing hooks with ease. You can read more about this package here.

As for hooks, there's https://react-hooks-testing-library.com/

Use @testing-library/reacthooks

Now I don't need to worry about React lifecycle methods. I can test my hook if I want to, but it hardly seems worth it here. If I would, it would be easier to do so using react-hooks-testing-library

If you happen to be using React Testing Library in your project, you'll need to keep the jsdom dev dependency installed.

Readability.js requires a DOM object to parse the readable content from a website. That's why we create a DOM object with JSDOM and provide the HTML from the page and its current URL. By the way, the browser may have had to follow HTTP redirects, so the current URL doesn't necessarily have to be the one we provided initially. The parse function of the library returns the following result:

This was the basic usage of JSDOM. If you want to learn more, please check out this documentation.

Web scraping, while immensely useful, often requires developers to navigate a sea of tools and libraries, each with its own quirks and intricacies. Whether it's JSDOM, Cheerio, Playwright, or even just plain old vanilla JS in the DevTools console, moving between these platforms can be a challenge.

React testing library uses jsdom (or others like happy-dom) under the hood to emulate the browser environment and enable testing of different properties. but it doesn't render the component in an actual browser meaning the styles can't be computed and the returned computed style is just an object with the correct keys but empty strings as values.

Note: In order to use the library jsdom to scrape the HTML response we need to avoid the @import statements in the CSS.

The code uses jSDom to render the app but I was wondering if it's possible to run the app without the UI to be able to use a library like that to generate the string from react element.

JSDOM as the DOM environment for running our tests