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Andrew Clark
93c10dfa6b
If something throws as a result of `flushSync`, and there's remaining work left in the queue, React should keep working until all the work is complete. If multiple errors are thrown, React will combine them into an AggregateError object and throw that. In environments where AggregateError is not available, React will rethrow in an async task. (All the evergreen runtimes support AggregateError.) The scenario where this happens is relatively rare, because `flushSync` will only throw if there's no error boundary to capture the error.
react-test-renderer
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.