Make sure that jest tests fail if an error is thrown within a jsdom event handler

[sophiebits]

In a few situations in our unit tests, we use .dispatchEvent on a jsdom DOM node in order to use the jsdom event system:

react/src/renderers/dom/shared/wrappers/__tests__/ReactDOMInput-test.js

Line 127 in e612826

instance.a.dispatchEvent(inputEvent);

But it appears that if the event handler throws (ex: change the onChange handler in that test to throw), then the error is silently ignored and does not cause the test to fail.

jsdom does make some attempt to report an error:

https://github.com/tmpvar/jsdom/blob/9.8.3/lib/jsdom/living/events/EventTarget-impl.js#L235

We should hook into this in our jest config (scripts/jest/test-framework-setup.js) and see if we can fail any test that triggers this exception behavior. From the implementation of reportException it looks like we might be able to do an onerror handler; if that doesn't work then hooking into their "virtual console" may be possible.

[franciscofsales]

I tried playing around with this by catching the error event jsdom dispatches on window and it was kind of going fine but then I had conflicts with tests in here:

https://github.com/facebook/react/blob/master/src/renderers/shared/stack/reconciler/tests/ReactErrorBoundaries-test.js#L256

any ideas what I might be getting wrong?

[renderf0x]

Got this working using the onerror suggestion above; Added #8278 as a PR.

Edit: and low and behold, same issue as @franciscofsales . Good catch, closing the PR.

[franciscofsales]

@renderf0x that is exactly what I had done, apart from naming and comment. Not sure how to not trigger that issue.

[franciscofsales]

Got it. Added #8279. Thanks

[renderf0x]

@franciscofsales ah indeed. rad. we'd have to have FB confirm, but this probably just never was a problem because it wasn't being listened for (hence this issue). good stuff.

[franciscofsales]

@renderf0x yeah, I think so. I got the answer from your commit actually. I was spying on error turns out it's onerror. Thanks.