feat: Support Stylelint custom syntax object

[TJNhxMZHmqGytuWT]

The customSyntax option in Stylelint config can accept a module name, but it can also accept a Syntax object:

// .stylelintrc.js
module.exports = {
  customSyntax: require('postcss-less'),
};

Some examples in the wild:
https://github.com/search?q=%22customSyntax%3A+require%28%22&type=code

Since Knip assumes that config.customSyntax can only be a string, running it with this kind of config results in the following error:

export const isInNodeModules = (filePath) => filePath.includes('node_modules');
                                                      ^
TypeError: filePath.includes is not a function

I updated the Stylelint plugin to avoid trying to resolve syntax objects.

I also added tests for JS config files.

[pkg-pr-new]

Open in Stackblitz

npm i https://pkg.pr.new/knip@937

commit: 9178bb0

[webpro]

Thanks for the PR! Happy to merge, but please first see the feedback.

[webpro]

The idea of most of the plugin tests is to not leave any issues, so only the processed and total counters should not be zero (0). In other words, the dependencies referenced in the plugin config files in the fixtures should also be listed in package.json.

[TJNhxMZHmqGytuWT]

Alright! Thanks

[webpro]

Thanks!

Idea: if we'd remove the node_modules folder in the fixture folder, would we still get the same test results? This is usually necessary to have in certain situations with binaries and such. If it's not doing much we might as well delete it.

[webpro]

Maybe unknown would be better than object here?

[TJNhxMZHmqGytuWT]

Thanks!

Idea: if we'd remove the node_modules folder in the fixture folder, would we still get the same test results? This is usually necessary to have in certain situations with binaries and such. If it's not doing much we might as well delete it.

If we completely remove node_modules, we get some errors because some of these packages are directly imported with require() in Stylelint config files

But I removed the ones that weren't necessary!

[webpro]

Perfect, thank you!

[webpro]

🚀 This pull request is included in v5.44.1. See Release 5.44.1 for release notes.

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