special/eslint: bad calculation of preset dependencies

Bug Description

In a monorepo project managed by yarn, I have a package containing my eslint configuration. Every eslint needed dependency is set as a dependency (not dev!) of this package.

This is currently working because of 2 bugs, one masking the other:

• the method requireConfig of eslint.js only searches for configuration dependency in the current directory, therefore ignoring structures like yarn workspaces; it should use the new utils.loadMetadata function to use the real node resolution mechanism;
• when analyzing eslint configuration dependencies, it does not look at this dependencies’ dependencies.

In a normal environment (if I had a configuration package apart), the process would fail because it would be able to analyse the project configuration file, see that a lot of packages are needed, but not see that they already are integrated because dependencies of this configuration package, so displaying a lot of “missing dependencies”.

Code snippets

In the package @my-project/eslint-config:

File .eslintrc.yaml:

plugins:
  - react-hooks

File package.json:

  "dependencies": {
    "eslint-plugin-react-hooks": "2.2.0"
  }

In the package @my-project/other-package

File .eslintrc.yaml:

extends:
  - '@my-project'

File package.json:

  "devDependencies": {
    "@my-project/eslint-config": "0.0.1"
  }

Execution

In the directory of other-package:

depcheck --specials=eslint

Expected result

No error.

Actual result

• with a yarn workspace, no error because hoist eslint-config is not seen by the analyzer;
• with npm and lerna, missing dependencies: eslint-plugin-react-hooks because the analyzer sees the eslint-config but does not read its included dependencies.

Versions

• node -v: 12.13.0
• npm -v: 6.12.0
• yarn -v: 1.19.1
• depcheck --version: 0.9.1

Extra info

Sorry for not publishing a PR, but I can’t really spend more time on depcheck.

[rumpl]

🎉

I’ll buy you a beer next time you come to Paris 😃

[sveyret]

Finally, I’m working on it… 😄