Unlock the Power of Visual Regression Testing
When it comes to ensuring your app’s UI remains consistent and visually appealing, screenshot testing is a game-changer. By comparing screenshots of your app’s old and new UI, you can identify even the slightest visual regressions.
The Limitations of Code-Based Testing
While code-based testing is essential, it falls short when it comes to detecting visual regressions. That’s because it only inspects the code, not the actual image displayed in the browser. This is where screenshot testing comes in – providing a safety net to catch those pesky visual errors.
Jest Screenshot Testing Libs: A Comparison
Two popular Jest screenshot testing libraries for React are jest-image-snapshot and react-screenshot-test. Both utilize Puppeteer, a Node.js library that controls headless Chrome or Chromium, to take screenshots. But what sets them apart?
Setup and Usage Differences
jest-image-snapshot requires Puppeteer configuration on the app side, whereas react-screenshot-test encapsulates the entire process, providing its own API for screenshot testing. Installation involves setting up jest-image-snapshot by adding an extra method to the Jest expect, while react-screenshot-test configuration lives in the jest.screenshot.config.js file.
Example Tests
A typical jest-image-snapshot test involves launching a browser, opening a page, navigating, and taking a screenshot. The react-screenshot-test, on the other hand, has its own minimal and convenient API for testing.
Running Tests Locally
To run tests locally, jest-image-snapshot needs the app to be served using a web server, while react-screenshot-test requires a simple command execution.
The Verdict
Both libraries offer unique benefits. jest-image-snapshot is ideal for projects already using Puppeteer for e2e tests, while react-screenshot-test excels at pairing components with screenshots of various options and screen resolutions.
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