Allow instrumentation of transformed files with weird file extensions

[andersk]

Summary

The default configuration of babel-plugin-istanbul only allows instrumentation of files with extensions .js, .cjs, .mjs, .ts, .tsx, .jsx (https://github.com/istanbuljs/schema/blob/v0.1.2/index.js#L71). However, we know that we’re running it on code that we just transformed to JavaScript, so the source language no longer matters, and we should disable this check to get complete instrumentation.

Test plan

With the example project at https://github.com/andersk/jest-handlebars-test, before:

$ jest --coverage --no-cache
 PASS  __tests__/greet.js
  ✓ am (3ms)

----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |       0 |        0 |       0 |       0 |                   
----------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        0.443s
Ran all test suites.

and after:

$ jest --coverage --no-cache
 PASS  __tests__/greet.js
  ✓ am (4ms)

-----------|---------|----------|---------|---------|-------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
-----------|---------|----------|---------|---------|-------------------
All files  |      75 |    66.67 |   66.67 |   66.67 |                   
 greet.hbs |      75 |    66.67 |   66.67 |   66.67 | 4                 
-----------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        0.551s
Ran all test suites.

[SimenB]

Thanks! This makes sense to me. Could you add an integration test as well? We have some for coverage already

[andersk]

Okay, I’ve added my example project as an integration test.

[SimenB]

Perfect, thank you! Just running prettier/eslint on the one file and we should be good to go 🙂

[andersk]

Just to make sure I did the right thing here: I added an exemption to checkCopyrightHeaders for e2e/coverage-handlebars. (I don’t care so much, but since the CLA isn’t a copyright transfer, I didn’t want to claim that my code is © Facebook.)

I left the copyright header on e2e/__tests__/coverageHandlebars.test.ts, which is copied from coverageRemapping.test.ts and coverageTransformInstrumented.test.ts.

[SimenB]

I honestly have no idea what the header is for, but just adding the header seems easiest. The blacklist is for stuff like vendored modules and config files, I think, but this is code (albeit tests)

[codecov-io]

Codecov Report

Merging #9589 into master will increase coverage by 0.01%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master    #9589      +/-   ##
==========================================
+ Coverage   65.06%   65.07%   +0.01%     
==========================================
  Files         286      287       +1     
  Lines       12137    12141       +4     
  Branches     3007     3008       +1     
==========================================
+ Hits         7897     7901       +4     
  Misses       3605     3605              
  Partials      635      635

Impacted Files	Coverage Δ
packages/jest-transform/src/ScriptTransformer.ts	69.64% <ø> (ø)	⬆️
e2e/coverage-handlebars/greet.hbs	50% <50%> (ø)
packages/expect/src/utils.ts	96.22% <0%> (+1.25%)	⬆️

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[andersk]

Eh, I guess I’m willing to claim to be an “affiliate” for this purpose. Updated.

[codecov-io]

Codecov Report

Merging #9589 into master will decrease coverage by <.01%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master    #9589      +/-   ##
==========================================
- Coverage   65.06%   65.06%   -0.01%     
==========================================
  Files         286      287       +1     
  Lines       12137    12141       +4     
  Branches     3007     3010       +3     
==========================================
+ Hits         7897     7899       +2     
- Misses       3605     3606       +1     
- Partials      635      636       +1

Impacted Files	Coverage Δ
packages/jest-transform/src/ScriptTransformer.ts	69.64% <ø> (ø)	⬆️
e2e/coverage-handlebars/greet.hbs	50% <50%> (ø)

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[github-actions]

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