(jest) improves performance and mem use reduction; adds compatibility with 3rd party tools; fwds all args to jest command

[dac09]

Closes #2708
Closes #4017
Closes #3413
Closes #3419

What does this do?

Changes how jest is configured in the following ways:

1. adds a root jest.config.js to Redwood projects. This is required for other tools (and the jest cli itself) to know what config to load. (See examples section)
2. removes the need for packages/testing/config/jest/jest.config.js, as I've moved this code into the presets i.e. packages/testing/config/jest/api/jest-preset.js and packages/testing/config/jest/web/jest-preset.js. We don't need to pass this hidden config file anymore
3. in the web/jest.config.js and api/jest.config.js - we now use presets, instead of importing the module. Why? This seems to work better with tooling e.g. Wallaby (see examples)
4. Moves logic for prisma reset from the cli, to jest-preset. This ensures the scenarios work even without the redwood cli.
5. Keeps backward compatibility - i.e. if you don't use the new web/jest.config.js, ./jest.config.js and api/jest.config.js in your project, it will still work as before
6. Include's @callingmedic911 fix for coverage folder in Fix: Jest not using the project root config #4059

Examples & Why things are done this way

[dac09]

@jtoar can I request you take a look at this too please? We have a few jest PRs in progress, I think this one should go last

[callingmedic911]

I also checked out locally and tested this. Looks good! I left a few minor subjective suggestions. We now just need to rebase on main to include parallel execution change.

Lastly, do you think I should close #4059?

Over to you and @jtoar for the final call. :)

[dac09]

Note
Due to the other changes we've made recently to jest-config, Wallaby doesn't work out of the box for the api side. To get it working you need to add an extra line to api/jest.config.js.

const config = {
  rootDir: '../',
  preset: '@redwoodjs/testing/config/jest/api',
}
+ if (process.env.DEBUG?.includes('wallaby')) config.runner = 'jest-runner';
module.exports = config

[dac09]

@thedavidprice gone through the checklist

@dac09 Final checklist I suggest to move this one to merge:

* [x]  Add a section to [redwoodjs.com/docs/testing](https://redwoodjs.com/docs/testing) about Jest Config, including the 3 config files and code for each: explain how it works and why it's need to be compatible with the ecosystem

PR created here: https://github.com/redwoodjs/redwoodjs.com/pull/959

Can you please confirm you're happy with the title of the page? I'll update all the links

  * add commented links to this section of Docs in crwa/template/ (see specific comments for each of the 3 files)

Will need updating

* [x]  Determine what to do about [Running tests with multiple "--coverageReporters" options #3419](https://github.com/redwoodjs/redwood/issues/3419) (if not able to resolve here)

Added fix for this also. Thanks for scope creep 😉 ✌️

* [ ]  Determine when to handle check for config in web/ and api/ ([comment above](https://github.com/redwoodjs/redwood/pull/4096#issuecomment-1024810384))

I want to discuss this further, but also don't think we need this in the PR, its already grown too much in scope I think!

* [x]  Being able to foward all commands to Jest is a big improvement. Can you update the PR title to mention this as well so we call it out better?

Done

* [ ]  I need copy to include in Release Notes
  
  * briefly explaining changes here (the "why") and that they're backwards compatible
  * explain how to upgrade to new config (you're going to add a codemod, aren't you? 😂)

I don't think we need a codemod because its backwards compatible. If you're happy with your jest config, then probably no need to change!

Blurb:
We've improved our jest configuration so that
a) It uses about 40-50% less memory
b) Its easier to use whatever tools you usually use to run your tests, instead of just through the redwood cli. Infact, its pretty vanilla now, so if you wish you can directly run the jest cli from the commandline yarn jest and it'll pick up all the redwood settings! Checkout the forums, if you're looking for how to use redwood's test with your tool of choice.

[orta]

Nice, I think this is enough to run wallabyjs on redwood tests, it's my only current codebase which doesn't work with it

[dac09]

It is! Been my personal mission, also ❤️ wallaby. It does need a little tweak to the config though (see my first comment on this pr)

[thedavidprice]

Performance

I did a quick mem before and after check and reported it over here in #4208

Confirming Web seems resolved and API is reduced but about 50%. 🚀

[thedavidprice]

So very solid. Huge lift here @dac09 Well done 🚀

I'm working with @dac09 on docs and other next steps. Will get this into forthcoming release.