Unexpected istanbul code coverage

[sagargurtu]

Describe the bug

For v1.4.0, istanbul shows exported string constants as not covered. This is a deviation from v0.34.6 where it correctly skips string constants in code coverage.

Is this an expected change in behavior? Or a bug?

Reproduction

See terminal for coverage results:

• v1.4.0 https://stackblitz.com/edit/vitest-dev-vitest-dy65uu
• v0.34.6 https://stackblitz.com/edit/vitest-dev-vitest-sxb7gh

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (3) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 18.18.0 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.3 - /usr/local/bin/npm
    pnpm: 8.15.3 - /usr/local/bin/pnpm
  npmPackages:
    @vitest/coverage-istanbul: 0.34.6 => 0.34.6 
    vite: ^5 => 5.2.6 
    vitest: 0.34.6 => 0.34.6

Used Package Manager

npm

Validations

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• Read the Contributing Guidelines.
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• The provided reproduction is a minimal reproducible example of the bug.

[AriPerkkio]

In Vitest v1 we enabled coverage.all by default:

• feat!: enable coverage.all by default #4265

Add this option in your v0.34.6 and you should see the same results. Or disable it in the v1.4.0 reproduction.

[sagargurtu]

I see. Thanks for the info! Will close this issue.

However, is it valid for coverage to be collected for an exported string constant (or an exported number or boolean)? Would the recommendation be to write a test that checks if the value is as expected 🤔? I just wanted to export a public constant from my package and it feels weird to write a test to check its value.

[AriPerkkio]

However, is it valid for coverage to be collected for an exported string constant (or an exported number or boolean)?

Looks like Istanbul does add a statement counter there: https://evanw.github.io/source-map-visualization/#MTMzOQB....

You can use ignore hints or coverage.exclude for this. Personally I think I would add test case for the file that actually imports this file. Then it would become covered automatically.