Скачать или смотреть How to Properly Test window.location.href Changes in React with Jest and Testing Library

Learn the best practices for unit testing `window.location.href` changes on button clicks in React components using Jest and React Testing Library.
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Debugging window.location.href Changes with Jest and React Testing Library

Unit testing is an essential part of modern web development, especially when dealing with user interactions that affect the state of your application. A common scenario developers face is testing when window.location.href changes as a result of user actions, such as button clicks. In this guide, we'll explore a specific problem and its solution to properly test such changes in React components by leveraging tools like Jest and React Testing Library.

The Problem

You might find yourself in a situation where a button click in your React component updates window.location.href. While testing this interaction, you want your tests to accurately simulate user behavior instead of manually setting the URL in your test code. For instance, directly assigning window.location.href = 'www.randomurl.com' will not accurately reflect whether your button click triggered the navigation as intended.

An example situation might involve a function (let's call it goToThisPage) that you want to test to ensure it was called following a button press. However, you can hit a snag where your tests fail due to improper mocking or function placements.

The Solution: Properly Mocking and Testing goToThisPage

To effectively test changes to window.location.href, here are two recommended approaches:

Example 1: Splitting the Function into Its Own File (Recommended)

Step 1: Move the function to a separate file. This approach simplifies mocking, as it ensures that the correct mocked version is used during testing.

goToThisPage.js:

[[See Video to Reveal this Text or Code Snippet]]

Component.jsx:

[[See Video to Reveal this Text or Code Snippet]]

Component.spec.jsx:

[[See Video to Reveal this Text or Code Snippet]]

Example 2: Not Recommended but Possible

If for some reason, splitting the function into a separate file is not feasible, you can instead use a proxy function that determines whether to call the actual function or the mocked version. However, note that this approach can lead to complexity and is generally not advisable.

Component.jsx:

[[See Video to Reveal this Text or Code Snippet]]

Component.spec.jsx:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

When it comes to unit testing in React, particularly when testing user interactions involving window.location.href, it is crucial to have proper mocking and implementation strategies. The recommended approach is to separate functions into their own files, significantly simplifying the mocking process and providing clearer tests. By following the best practices outlined in this blog, you'll find testing your React components seamless and more efficient.

For more discussions or questions around unit testing best practices, feel free to share your thoughts in the comments below.