fix (jest-runtime): correct wrapperLength value for ESM modules

[mrazauskas]

Summary

Resolves #11891.

v8 coverage reports were incorrect in ESM mode. Seems like wrapperLength value was the problem. If I got it right, transformFileAsync is called only in ESM mode. And if I get it right, the wrapper is CJS module wrapper. ESM is not using it, so perhaps the best solution is to keep the value of wrapperLength undefined. Simply: the wrapper does not exist.

Test plan

I started form failing tests. The failing ones were: esm-native-without-sourcemap and esm-with-custom-transformer.

It seemed useful to rename the v8 test directory by prefixing it with coverage- (coverage-provider-v8 instead of v8-coverage). This way all coverage related tests live next to each other. Easier to find them.

I created tests for both native cjs and native ems. The wrapperLength value is the imporntant difference, which has to be covered by tests. The wrapper is only important for v8 coverage.

cjs-native and esm-native tests are also proving that coverage report looks good if source map is not included. Here the source code is not transformed at all, hence we do not have source map. These two tests are fully replacing current no-sourcemap test, which I removed as unnecessary.

[SimenB]

this looks pretty good! I'd like to keep the existent test as is, but beyond that this LGTM 🙂

[mrazauskas]

@SimenB All (should be) fixed as suggested. Thanks for the review.

[codecov-commenter]

Codecov Report

Merging #11893 (6727a01) into main (da7c4a4) will decrease coverage by 0.13%.
The diff coverage is 54.05%.

@@            Coverage Diff             @@
##             main   #11893      +/-   ##
==========================================
- Coverage   68.87%   68.73%   -0.14%     
==========================================
  Files         312      322      +10     
  Lines       16432    16580     +148     
  Branches     4768     4784      +16     
==========================================
+ Hits        11318    11397      +79     
- Misses       5087     5150      +63     
- Partials       27       33       +6     

Impacted Files	Coverage Δ
...vider-v8/cjs-native-without-sourcemap/uncovered.js	0.00% <0.00%> (ø)
...ge-provider-v8/cjs-with-babel-transformer/types.ts	0.00% <0.00%> (ø)
...rovider-v8/cjs-with-babel-transformer/uncovered.ts	0.00% <0.00%> (ø)
e2e/coverage-provider-v8/empty-sourcemap/types.ts	100.00% <ø> (ø)
...vider-v8/esm-native-without-sourcemap/uncovered.js	0.00% <0.00%> (ø)
...e-provider-v8/esm-with-custom-transformer/types.ts	0.00% <0.00%> (ø)
...ovider-v8/esm-with-custom-transformer/uncovered.ts	0.00% <0.00%> (ø)
e2e/coverage-provider-v8/no-sourcemap/Thing.js	100.00% <ø> (ø)
e2e/coverage-provider-v8/no-sourcemap/x.css	100.00% <ø> (ø)
packages/jest-runtime/src/index.ts	56.44% <ø> (ø)
... and 15 more

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[SimenB]

thanks!

[SimenB]

https://github.com/facebook/jest/releases/tag/v27.2.2

[github-actions]

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