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* Extract base Jest config This makes it easier to change the source config without affecting the build test config. * Statically import the host config This changes react-reconciler to import HostConfig instead of getting it through a function argument. Rather than start with packages like ReactDOM that want to inline it, I started with React Noop and ensured that *custom* renderers using react-reconciler package still work. To do this, I'm making HostConfig module in the reconciler look at a global variable by default (which, in case of the react-reconciler npm package, ends up being the host config argument in the top-level scope). This is still very broken. * Add scaffolding for importing an inlined renderer * Fix the build * ES exports for renderer methods * ES modules for host configs * Remove closures from the reconciler * Check each renderer's config with Flow * Fix uncovered Flow issue We know nextHydratableInstance doesn't get mutated inside this function, but Flow doesn't so it thinks it may be null. Help Flow. * Prettier * Get rid of enable*Reconciler flags They are not as useful anymore because for almost all cases (except third party renderers) we *know* whether it supports mutation or persistence. This refactoring means react-reconciler and react-reconciler/persistent third-party packages now ship the same thing. Not ideal, but this seems worth how simpler the code becomes. We can later look into addressing it by having a single toggle instead. * Prettier again * Fix Flow config creation issue * Fix imprecise Flow typing * Revert accidental changes
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.