await for async jest config

[hisco]

Summary

Currently jest cli require the dynamic config module synchronously, this PR enables loading jest config module async.

Test plan

Tested project using yarn test - got some issues not related to my change:

/jest/packages/jest-haste-map/src/lib/FSEventsWatcher.ts
14:1  error  Unused eslint-disable directive (no problems were reported)
/jest/packages/jest-transform/src/ScriptTransformer.ts
578:3  warning  Arrow function expected no return value  consistent-return
594:3  warning  Arrow function expected no return value  consistent-return

In addition created a tiny project and tested the async config module using yarn link - no issues were observed.

[scotthovestadt]

You can run tests with yarn jest, looks like there are a few failing.

Can you give me an example of how this is used and also update documentation with that as well?

[hisco]

@scotthovestadt thanks

• I run yarn test the falling tests indeed show up.
• Updated the contribution section.
• Updated the configuration section.

I added an example of such use is in the docs section, here a more advanced section:

import * as request from 'request-promise';
export async ()=>{
  return await request('http://some-remote')
}

Basically for my use cases, I found a way to do it synchronically, I think it would be much nicer to do it async.

[SimenB]

Please add a test (integration test perhaps?) with async config. Also please update the changelog and fix the linting error reported by CI 🙂

---

This is technically a breaking change if anybody else uses jest-config to load jest's config instead of letting Jest itself do it. Is that ok?

[jeysal]

+1 for breaking, put it in a major 😅

[hisco]

@SimenB I didn't notice any integration test for current implementation, do you have an idea how to mock this scenario?

Thanks in advance!

[SimenB]

This is a really small breaking change, so we can land it in 25. @hisco could you rebase on master?

[hisco]

@SimenB I did, unfortunately it's completely broken:
Latest commit broke it (6bd4e560e288b515ebdf8325f6219522f538dbec)
At commit 8d0b5e2234d378920eb87112933c5c03016fb98e everything was working properly.

[SimenB]

@hisco sorry, I missed your answer, then completely forgot about this 😬

I made readConfig async as part of support jest.config.mjs in #9431, so most of the changes in this PR are already on master (and it is no longer breaking as the breaking changes are already landed). It should be a matter of invoking the function after loading in packages/jest-config/src/readConfigFileAndSetRootDir.ts and adding a test plus updating docs. Are you up for finishing this, by any chance?

[SimenB]

@hisco ping 🙂

[hisco]

It seems that most of my changes are already in master I don't think it's a result of a merge with my code so I won't take the credit...
The only thing missing was the docs, please use #10001 instead it's a much cleaner branch.

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