proposal: Cache base run results to speed up tests

[sidharthv96]

We can use the @actions/cache package to cache the last baseRun report with the base commit hash as key.
So, we can run the action 2x faster for big repos having lots of tests.

[ArtiomTr]

Sound good! Thank you for your idea!

[sidharthv96]

The POC is ready, but running into some issue with the cache service.

[FDiskas]

This is actually super cool idea.
Store report.json as a cache key from base commit hash and use https://github.com/actions/cache#skipping-steps-based-on-cache-hit to skip tests if report is available :)
please do not forget this :) it could improve in some case the 2x speed

[ArtiomTr]

Hello @FDiskas 👋,

Yes, the idea is great, however, it is impossible to use @actions/cache without breaking current functionality.
Cache is not working with composite actions due to security limitations. By using standard node12 or node16 runners users will lose the ability to manually setup node environment.

Similar functionality could be achieved by using base-coverage-file option. You should manually collect coverage, and then restore it.

[vgrafe]

fwiw and if it helps, when implementing my own action I did not run into problems caching test results (with key based on the commit sha) while similarily running a composite action: https://github.com/vgrafe/jest-reports/blob/main/src/getCoverageForSha.ts#L21.

Apologies if I missed something out.

[ArtiomTr]

Hello @vgrafe 👋,

Thank you for the suggestion, I will try it out.