Jest ignores Errors thrown by async functions in some cases

[bvaughn]

I recently noticed that Jest seems to ignore errors thrown by async functions in certain cases.

I discovered this while writing some tests for a React component that calls an async function from componentDidMount. If the async function calls setState- and the component un-mounts before that happens- the resulting warning/error issued by React is silently swallowed.

Here is an annotated example of what I'm describing (but without React):
https://github.com/bvaughn/jest-uncaught-error-repro/blob/master/index.test.js

To repro this false positive:

git clone [email protected]:bvaughn/jest-uncaught-error-repro.git
cd ./jest-uncaught-error-repro
yarn install
yarn test

In my repro, throwing the error within an expect(...).not.toThrow() block "fixes" things so that the test fails, but that is not the case within the test that first uncovered this issue. It's also not a great solution, since errors aren't guaranteed to be thrown within such a block.

Am I missing or overlooking something?

[bvaughn]

Maybe related to #5311, #3251 - although I added logging (to my local Jasmine Env) to verify that my error is thrown before the uncaught error handler is removed FWIW.

[bvaughn]

It was pointed out to me that this:

await Promise.resolve(r => setTimeout(r, 200));

...was a bit bogus and should instead be this:

await new Promise(r => setTimeout(r, 200));

...which does indeed seem to fix my repro.

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