Andrew Clark
857ee8cdf9
This disables symbol renaming in production builds. The original variable and function names are preserved. All other forms of compression applied by Closure (dead code elimination, inlining, etc) are unchanged — the final program is identical to what we were producing before, just in a more readable form. The motivation is to make it easier to debug React issues that only occur in production — the same reason we decided to start shipping sourcemaps in #28827 and #28827. However, because most apps run their own minification step on their npm dependencies, it's not necessary for us to minify the symbols before publishing — it'll be handled the app, if desired. This is the same strategy Meta has used to ship React for years. The React build itself has unminified symbols, but they get minified as part of Meta's regular build pipeline. Even if an app does not minify their npm dependencies, gzip covers most of the cost of symbol renaming anyway. This saves us from having to ship sourcemaps, which means even apps that don't have sourcemaps configured will be able to debug the React build as easily as they would any other npm dependency.
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react-test-renderer is deprecated and no longer maintained.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.