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[Bug]: V8 coverage does not work with native ESM

See original GitHub issue

Version

27.2.0

Steps to reproduce

As it was mentioned in https://github.com/facebook/jest/issues/9430#issuecomment-924826080, I was trying out V8 coverage with native ESM. Babel coverage works well, but for some reason there are issues with V8 coverage.

I was testing:

ESM without transforming, hence without source maps included
TypeScript modules transformed into ESM with source maps included

@SimenB thanks for quick response and hints. I started from creating failing tests inside a clone of Jest repo. The same result – coverage works well with Babel, but not with V8. So I will dig into the code and will try to find the reason.

Expected behavior

I also tried out coverage using c8 module directly on an ESM file (without involving Jest). All is good. Quick, nice and precise.

Actual behavior

V8 coverage reports seems to be buggy.

Additional context

No response

Environment

System:
    OS: macOS 10.15.7
    CPU: (8) x64 Intel(R) Core(TM) i7-3615QM CPU @ 2.30GHz
  Binaries:
    Node: 16.9.1 - /usr/local/bin/node
    Yarn: 2.4.3 - /usr/local/bin/yarn
    npm: 7.21.1 - /usr/local/bin/npm

Issue Analytics

State:
Created 2 years ago
Comments:8 (4 by maintainers)

Top GitHub Comments

1reaction

bompuscommented, Sep 22, 2021

I’m also experiencing this on 27.2.1 with --coverage=true --coverageProvider=v8. I didn’t check covered lines closely, but uncovered lines are off by ~3 lines it seems.

Running through c8 and using --coverage=false on jest, the uncovered line numbers are correct.

0reactions

github-actions[bot]commented, Oct 26, 2021

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs. Please note this issue tracker is not a help forum. We recommend using StackOverflow or our discord channel for questions.

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