adds createTestInstance function to ReactTestRenderer

[petegleeson]

Hello, I have had a crack at solving #12753. This change gives people the ability to traverse a component tree rendered by ReactDOM in a sanctioned way. Having a public API that provides this ability will be useful for testing libraries like Enzyme.

This is the most straight forward approach I could come up with. Would love opinions on whether this is the right package to expose this functionality.

Some todos:

• Documentation
• A more realistic test that uses ReactDOM

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[pull-bot]

Details of bundled changes.

Comparing: 79a740c...7125628

react-test-renderer

File	Filesize Diff	Gzip Diff	Prev Size	Current Size	Prev Gzip	Current Gzip	ENV
react-test-renderer.development.js	+0.1%	+0.1%	340.4 KB	340.75 KB	73.61 KB	73.69 KB	UMD_DEV
react-test-renderer.production.min.js	🔺+0.3%	🔺+0.2%	45.81 KB	45.93 KB	14.19 KB	14.22 KB	UMD_PROD
react-test-renderer.development.js	+0.1%	+0.1%	331.23 KB	331.58 KB	70.87 KB	70.96 KB	NODE_DEV
react-test-renderer.production.min.js	🔺+0.3%	🔺+0.2%	44.91 KB	45.03 KB	13.74 KB	13.76 KB	NODE_PROD
ReactTestRenderer-dev.js	+0.1%	+0.1%	337.13 KB	337.52 KB	70.46 KB	70.55 KB	FB_WWW_DEV

Generated by 🚫 dangerJS

[petegleeson]

Something to note - the implementation of this function assumes that wrapped node was created by TestRenderer. Not sure if this will cause problems when ReactTestInstance wraps nodes rendered by ReactDOM.

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contribution.

[stale]

Closing this pull request after a prolonged period of inactivity. If this issue is still present in the latest release, please ask for this pull request to be reopened. Thank you!