Sebastian Markbåge
ad578aa01f
Stacked on #34510. The "Commit" phase for a View Transition starts before the snapshot phase (before mutation) and then stretches into the async gap of `startViewTransition`, encompasses the mutation phase inside of its update callback and finally the layout phase. However, between the mutation phase and the layout phase we may suspend the start of the view transition on fonts and/or images. In that case we now split the Commit phase into first one before we suspend and then we log "Waiting for Images and/or Fonts" and then another Commit phase around the layout effects. <img width="897" height="119" alt="Screenshot 2025-09-16 at 11 37 26 PM" src="https://github.com/user-attachments/assets/0fe21388-bb48-4456-a594-62227d12d9b7" />
react-test-renderer (DEPRECATED)
Deprecation notice
react-test-renderer is deprecated and no longer maintained. It will be removed in a future version. As of React 19, you will see a console warning when invoking ReactTestRenderer.create().
React Testing
This library creates a contrived environment and its APIs encourage introspection on React's internals, which may change without notice causing broken tests. It is instead recommended to use browser-based environments such as jsdom and standard DOM APIs for your assertions.
The React team recommends @testing-library/react as a modern alternative that uses standard APIs, avoids internals, and promotes best practices.
React Native Testing
The React team recommends @testing-library/react-native as a replacement for react-test-renderer for native integration tests. This React Native testing-library variant follows the same API design as described above and promotes better testing patterns.
Documentation
This package provides an experimental React renderer that can be used to render React components to pure JavaScript objects, without depending on the DOM or a native mobile environment.
Essentially, this package makes it easy to grab a snapshot of the "DOM tree" rendered by a React DOM or React Native component without using a browser or jsdom.
Documentation: https://reactjs.org/docs/test-renderer.html
Usage:
const ReactTestRenderer = require('react-test-renderer');
const renderer = ReactTestRenderer.create(
<Link page="https://www.facebook.com/">Facebook</Link>
);
console.log(renderer.toJSON());
// { type: 'a',
// props: { href: 'https://www.facebook.com/' },
// children: [ 'Facebook' ] }
You can also use Jest's snapshot testing feature to automatically save a copy of the JSON tree to a file and check in your tests that it hasn't changed: https://jestjs.io/blog/2016/07/27/jest-14.html.