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## Overview Does a few things: - Renames `enableSyncDefaultUpdates` to `forceConcurrentByDefaultForTesting` - Changes the way it's used so it's dead-code eliminated separate from `allowConcurrentByDefault` - Deletes a bunch of the gated code The gates that are deleted are unnecessary now. We were keeping them when we originally thought we would come back to being concurrent by default. But we've shifted and now sync-by default is the desired behavior long term, so there's no need to keep all these forked tests around. I'll follow up to delete more of the forked behavior if possible. Ideally we wouldn't need this flag even if we're still using `allowConcurrentByDefault`.
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.