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a1dbb852c2
We have behaviour divergence for act() between prod and dev (specifically, act() + concurrent mode does not flush fallbacks in prod. This doesn't affect anyone in OSS yet) We also don't have a good story for writing tests in prod (and what from what I gather, nobody really writes tests in prod mode). We could have wiped out act() in prod builds, except that _we_ ourselves use act() for our tests when we run them in prod mode. This PR is a compromise to all of this. We will log a warning if you try to use act() in prod mode, and we silence it in our test suites.
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://facebook.github.io/jest/blog/2016/07/27/jest-14.html.