resolve.alias does not resolve correctly when been resolved as soft links in node_modules

[JounQin]

Describe the bug

----------------------------------|---------|----------|---------|---------|-------------------

File	% Stmts	% Branch	% Funcs	% Lines	Uncovered Line #s
All files	0.84	0	0	1.18
eslint-mdx/lib	0	0	0	0
index.es2015.mjs	0	0	0	0	5-196
eslint-mdx/src	0.73	0	0	1.17
helpers.ts	0	0	0	0	1-140
index.ts	100	100	100	100
meta.ts	0	100	100	0	1-3
parser.ts	0	0	0	0	1-100
sync.ts	0	100	100	0	1-11
tokens.ts	0	0	0	0	6-272
worker.ts	0	0	0	0	3-775
eslint-plugin-mdx/lib	0	0	0	0
index.es2015.mjs	0	0	0	0	7-508
eslint-plugin-mdx/src	33.33	0	0	45.45
helpers.ts	0	0	0	0	1-15
index.ts	100	100	100	100
meta.ts	0	100	100	0	1-3
eslint-plugin-mdx/src/configs	0	0	0	0
base.ts	0	100	100	0	3
code-blocks.ts	0	100	100	0	3
flat.ts	0	100	100	0	2-30
index.ts	0	100	0	0	3-11
overrides.ts	0	0	100	0	2-13
recommended.ts	0	0	0	0	1-95
eslint-plugin-mdx/src/processors	0	0	0	0
helpers.ts	0	0	0	0	1-23
index.ts	0	100	0	0	1-8
options.ts	0	0	0	0	9-55
remark.ts	0	0	0	0	2-67
eslint-plugin-mdx/src/rules	0	0	0	0
index.ts	0	100	0	0	2-8
remark.ts	0	0	0	0	1-115
----------------------------------	---------	----------	---------	---------	-------------------

I'd expect no eslint-mdx/lib and eslint-plugin-mdx/lib files here.

Reproduction

https://github.com/mdx-js/eslint-mdx/actions/runs/7378227896/job/20073106362?pr=508#step:6:27

https://github.com/mdx-js/eslint-mdx/tree/build/yarn_v4

System Info

System:
    OS: macOS 14.2.1
    CPU: (10) arm64 Apple M1 Max
    Memory: 11.77 GB / 64.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.10.0 - ~/Library/Caches/fnm_multishells/89034_1703864877615/bin/node
    Yarn: 4.0.2 - ~/Library/Caches/fnm_multishells/89034_1703864877615/bin/yarn
    npm: 10.2.3 - ~/Library/Caches/fnm_multishells/89034_1703864877615/bin/npm
    bun: 1.0.20 - /opt/homebrew/bin/bun
  Browsers:
    Brave Browser: 120.1.61.109
    Chrome: 120.0.6099.129
    Safari: 17.2.1
  npmPackages:
    @vitest/coverage-istanbul: ^1.1.1 => 1.1.1 
    vitest: ^1.1.1 => 1.1.1

Used Package Manager

yarn

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[sheremet-va]

I'd expect no eslint-mdx/lib and eslint-plugin-mdx/lib files here.

Why you don't expect them?

[JounQin]

Because I have resolve.alias settings with eslint-mdx/eslint-plugin-mdx? eslint-mdx/src/index.ts should be resolved.

[sheremet-va]

And how is node_modules involved here? This is hardly a minimal reproduction.

[JounQin]

@sheremet-va Yes, this could be a complicated issue.

I'm using eslint-plugin-mdx@link:packages/eslint-plugin-mdx.

See also https://github.com/mdx-js/eslint-mdx/blob/cf077e5e0e6d85ccb4dbeca142cb6e30e67dde8d/package.json#L60

eslint will resolve mdx plugin automatically in the test cases. (Non-flat config mode)

[sheremet-va]

resolve.alias is used only for:

• static/dynamic imports using ESM syntax (await import or import * from)
• the file that does the import is processed (inlined) by Vitest. Libraries by default are not inlined if Node.js can process them without Vite (file is correct CJS/ESM file). This is a performance optimization

So, try adding the library to server.deps.inline first.

[JounQin]

@sheremet-va Seems not working neither.

[sheremet-va]

Inlining your own package doesn't do anything - your source code is already inlined. The option is located inside deps name because it is meant to list dependencies that need inlining. On your screenshot, you also don't have any aliases.

[JounQin]

So what should I do then? I can not inline eslint because I have to use setup file which includes a specific eslint subpath to preload it for testing. This approach works well with jest.

See also https://github.com/mdx-js/eslint-mdx/blob/master/package.json#L86-L88

[sheremet-va]

I don't know how linter.js file works, so I cannot give any recommendations. All I can say is that supporting aliases and transformations in require is out of scope for Vitest. For aliases to apply, the file should be processed by Vitest, and the module should be imported using import. By default, all files outside of node_modules are processed. You have ./lib in your coverage because it was included somehow.

[sheremet-va]

Also, it's possible that you have this file in your coverage because coverage includes all files under "include" by default. You can disable it with this config:

export default {
  test: {
    coverage: {
      all: false
    }
  }
}

Or you can also include only required files:

export default {
  test: {
    coverage: {
      include: ['./packages/*/src/**/*.ts']
    }
  }
}

[JounQin]

The main issue is eslint will load the eslint-plugin-mdx and run some test cases, but if lib folder is resolved, the coverage reported will be totally unexpected, eslint related test cases will not increase the coverage because of the lib folder.

[sheremet-va]

The issue with the coverage has nothing to do with resolve.alias. I checked that adding all: false to coverage options doesn't show any files that were not running during tests. I am closing the issue now.

[JounQin]

@sheremet-va I don't quite understand what's your meaning.

[sheremet-va]

@sheremet-va I don't quite understand what's your meaning.

Use this config options for coverage:

export default defineConfig({
  test: {
    coverage: {
      provider: 'istanbul',
      all: false,
    }
  }
})

It will only include files that you import in your tests.

[JounQin]

@sheremet-va Is that really working as expected? Only the index.ts files are covered...

[sheremet-va]

cc @AriPerkkio

[AriPerkkio]

Files that were loaded through Vite are present on coverage report. I guess ESLint loads your files using require?

Minimal reproduction would also be nice. I'm not quite sure what I'm looking at here.

[JounQin]

I guess ESLint loads your files using require?

Yes.

---

OK, I'll try to provide a minimal reproduction.

[AriPerkkio]

There's some discussion about coverage and require here:

• How to get code coverage for scripts called as worker process/thread? #3851
• Instrument spawned processes with ts-node #2911

But the main thing is that Vite intercepts only import and import(). Code that is run using require, child_process or worker_threads is not transformed. Vitest features like coverage and mocks won't work there.

[JounQin]

Thanks for your references, I think I have to stick on jest for now.