feat(runtime): add support for async code transformation

[SimenB]

Summary

Fixes #9504

Test plan

e2e test added

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Deploy preview for jestjs ready!

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Deploy preview for jestjs ready!

Built without sensitive environment variables with commit 507c635

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[thymikee]

Is it worth to add a test for async .mjs transform as well?

[codecov-io]

Codecov Report

Merging #11191 (507c635) into master (858c50b) will decrease coverage by 0.04%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master   #11191      +/-   ##
==========================================
- Coverage   64.31%   64.27%   -0.05%     
==========================================
  Files         307      307              
  Lines       13444    13458      +14     
  Branches     3281     3285       +4     
==========================================
+ Hits         8647     8650       +3     
- Misses       4090     4101      +11     
  Partials      707      707              

Impacted Files	Coverage Δ
packages/jest-runtime/src/index.ts	54.85% <50.00%> (-0.74%)	⬇️

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[SimenB]

@thymikee this is ESM already as we cannot support async transformation for CJS, although via type: 'module' in package.json rather than mjs extension.

Or am I misunderstanding your question? 😅 Did you mean the transformer should be ESM?

[thymikee]

I meant the file to be my-transform.mjs and checking if a transform can be written in ESM instead of CJS. But I'm not really up to the speed with all the ESM changes, so pardon if I ask some dummy questions 🙈

[SimenB]

Ah! I added a test for that together with the feature in #11163.

This PR is that the transformation can be async, not transformers. Should rename something...

[thymikee]

Perfect, thanks! I see these are separate responsibilities, could have checked it before asking :)

[SimenB]

No problem 👍

[SimenB]

all of the type changes here should have been in #9889, but I didn't test writing a transformer before merging it, just calling it from runtime. So snuck it in here 😀

[ahnpnl]

Hmm, I observed something odd. After adopting next-5, transformer lost this value in getCacheKey and process when running with Node ESM. That doesn't occur with Node CommonJS. Is this behavior expected or is it a bug?

An example is

const path = require('path');

class MyTransformer {
    process(src, filename, config, options) {
         console.log('this value', this); // this is undefined when running Jest in ESM mode

         return 'module.exports = ' + JSON.stringify(path.basename(filename)) + ';';
    },
}

module.exports = {
  createTransformer: () => new MyTransformer(),
};

[SimenB]

Please open up a separate issue.

Note that we've never really supported using classes, so I don't think we've ever officially supported any form of this. However, I'm surprised this changed between next.4 and next.5

[ahnpnl]

oh nvm, i think something funky with my node_modules :)

[github-actions]

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