All coverage missing, minimal example

[donmccurdy]

I'm trying to use Vitest to report code coverage with a minimum viable library. The library is set up as shown below:

├── dist
|  ├── fibonacci.cjs
|  ├── fibonacci.cjs.map
|  ├── fibonacci.d.ts
|  ├── fibonacci.modern.js
|  └── fibonacci.modern.js.map
├── package.json
├── src
|  └── fibonacci.ts
├── test
|  └── fibonacci.test.ts
├── vitest.config.ts
└── yarn.lock

fibonacci_v01.zip

Note that package.json points to outputs in the dist/ folder, with sourcemaps, as defined here:

  "exports": {
    ".": {
      "types": "./dist/index.d.ts",
      "require": "./dist/fibonacci.cjs",
      "default": "./dist/fibonacci.modern.js"
    }
  },

Tests pass, but coverage is always empty:

yarn coverage
yarn run v1.22.22
$ vitest run --coverage

 RUN  v1.6.0 /Users/donmccurdy/Demos/2024-06-24_vitest_coverage_issue
      Coverage enabled with istanbul

 ✓ test/fibonacci.test.ts (1)
   ✓ fibonacci

 Test Files  1 passed (1)
      Tests  1 passed (1)
   Start at  11:00:39
   Duration  124ms (transform 20ms, setup 0ms, collect 14ms, tests 1ms, environment 0ms, prepare 38ms)

 % Coverage report from istanbul
--------------|---------|----------|---------|---------|-------------------
File          | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
--------------|---------|----------|---------|---------|-------------------
All files     |       0 |        0 |       0 |       0 |
 fibonacci.ts |       0 |        0 |       0 |       0 | 2-8
--------------|---------|----------|---------|---------|-------------------
✨  Done in 0.69s.

I'm experiencing the problem in a larger project, but stripped it down as much as possible to the fibonacci sample shown here. Things I've tried, without success:

1. Use @vitest/coverage-v8
2. Use @vitest/coverage-istanbul
3. Import directly from ../dist/fibonacci.modern.js in test, rather than from npm package name
4. Other combinations of coverage.include and coverage.all in vitest.config.ts

No errors or warnings, just 0% coverage. Does Vitest coverage support sourcemaps? Possible that this is related to v8 or istanbul, but given that the issue is happening with both, I thought I'd start opening a discussion here. Thanks!

[AriPerkkio]

Could you convert that zip-file into Github repository or use https://vitest.new ?

Does Vitest coverage support sourcemaps?

Yes, and we have test case for this:

• https://github.com/vitest-dev/vitest/blob/main/test/coverage-test/test/pre-transpiled-source.test.ts
• https://github.com/vitest-dev/vitest/tree/main/test/coverage-test/fixtures/src/pre-transpiled

The test case runs pre-transpiled.js and coverage report shows original.ts:

[donmccurdy]

Thanks @AriPerkkio! Here are both:

• https://github.com/donmccurdy/2024-06-24_vitest_coverage_issue
• https://stackblitz.com/edit/vitest-dev-vitest-r6x4s4?file=test%2Fbasic.test.ts

The stackblitz is a little different but I think shows the same issue. I notice there that if the tests imports from the src/ directory, coverage is shown, but imports from @vitest/example-test will print empty coverage. It would be preferable for me if the test suite could run against the builds in dist/, so that's why I wasn't importing from src/.

[AriPerkkio]

Thanks for minimal repros, it was easy to debug the root cause using those. 👍

This is a bug that's related to dist name specifically.

vitest/packages/vitest/src/defaults.ts

Lines 13 to 15 in 0eda99d

	export const defaultExclude = [
	'**/node_modules/**',
	'**/dist/**',

Here the defaultExclude is a hard coded default in Vitest. The this.options.exclude is what user sets in coverage.exclude. We should only use this.options.exclude here, and add defaultExclude to its default values. Then user could explicitly disable ignoring dist directory. Right now it's not possible as defaultExclude is always used.

vitest/packages/coverage-v8/src/provider.ts

Line 133 in 0eda99d

exclude: [...defaultExclude, ...defaultInclude, ...this.options.exclude],

vitest/packages/coverage-istanbul/src/provider.ts

Line 127 in 0eda99d

exclude: [...defaultExclude, ...defaultInclude, ...this.options.exclude],

So as work-around for now, rename your dist to something else. Could you verify if that works in your setup?

[donmccurdy]

Thanks @AriPerkkio, much appreciated! I've confirmed that renaming the dist folder to something else, like build, fixes the issue. For anyone else encountering this, I also needed to put the build folder (or whatever it's named, as long as it's not dist) in the "include" list for vitest:

import {defineConfig} from 'vitest/config';

export default defineConfig({
  test: {
    coverage: {
      provider: 'istanbul',
      include: ['src/**/*.ts', 'build/**/*'],
    },
  },
});

[AriPerkkio]

Great, let's follow fix in #5965.