try to resolve eslint relatively to nodePath

[BenoitZugmeyer]

Currently, coc-eslint tries to reslove the eslint module contained in a node_modules folder. This patch tries to resolve it locally first, then from the first parent-sibling node_modules folder.

Motivation

Yarn 2 (soon-to-be-released) is leveraging its "Plug'n'play" concept to the next level. Basycally, it doesn't store node modules in the node_modules folder anymore. As a workaround for tooling depending on node modules installed as a project dependency, it creates some modules files in a folder (currently named .vscode/pnpify/eslint). By setting nodePath to this folder, the extension should be able to resolve the needed source and binaries. The VSCode extension handle it correctly, but coc-eslint differs a bit and don't try to resolve the path relatively to nodePath.

[BenoitZugmeyer]

@chemzqm Thanks for merging my PR! Would you mind releasing it soon?

[chemzqm]

Fixed

[chemzqm]

@BenoitZugmeyer I can't understand how could eslint resolved from './eslint' directory, any documentation?

[BenoitZugmeyer]

Here is the related yarn documentation: https://yarnpkg.com/advanced/editor-sdks .

Basically, yarn 2 will not store eslint in the node_modules folder but rather in an arbitrary folder (named .yarn/sdks). Users of yarn 2 would like to specify the eslint.nodePath setting to indicate where to find the eslint module.

Now, the issue is: the coc-eslint resolveModule function will work like the Node.js require.resolve function (this is over-simplified but you get the picture):

• specifying "eslint" will look into node_modules folders relative to the paths given as argument
• specifying "./eslint" will look directly into the folders given as argument

So, if we use only resolveModule("eslint", ...) the ESLint install has to be in a node_modules folder. This breaks eslint resolution if it is not in a node_modules folder, no matter what eslint.nodePath is pointing to.

Here is how the vscode extension is handling it: https://github.com/microsoft/vscode-eslint/blob/master/server/src/eslintServer.ts#L761-L763 . It starts to resolve the eslint folder relative to the nodePath setting, then uses whatever paths it determined for traditional package manager installs (namely, ./node_modules folder)