💡 Add eslint-import-resolver-<resolver-name> support

[ronbraha]

Suggest an idea for this project

While onboarding Knip on one of the business repositories, I noticed that while the Knip ESLint plugin has broad support for automatically picking up dependencies that ESLint uses (especially with the new flat config), it still does not recognize import resolvers.
Is that something you considered adding support for?

Current day, I have to add eslint-import-resolver-webpack to ignoreDependencies manually.

[webpro]

There is some support and coverage for this in the ESLint plugin:

knip/packages/knip/src/plugins/eslint/helpers.ts

Line 104 in 3ee0476

return `eslint-import-resolver-${key}`;

Can you please show a complete reproduction of (relevant) config?

[guillaumebrunerie]

Same problem here, it worked before with a .eslintrc but then stopped working when I upgraded my ESLint config to a flat config.

Can be reproduced with the following eslint.config.js in a new project:

npm create vite@latest knip-import-resolver-test -- --template vanilla-ts`
cd knip-import-resolver-test
npm install eslint @eslint/js typescript-eslint eslint-plugin-import eslint-import-resolver-typescript knip

// eslint.config.js
import importPlugin from 'eslint-plugin-import';
import js from '@eslint/js';
import tseslint from "typescript-eslint";

export default [
	js.configs.recommended,
	...tseslint.configs.recommended,
	importPlugin.flatConfigs.recommended,
	{
		files: ['**/*.{ts,tsx}'],
		settings: {
			"import/parsers": {
				"@typescript-eslint/parser": [".ts", ".tsx"],
			},
			"import/resolver": {
				typescript: true,
				node: true,
			},
		},
		rules: {
			/* [...] */
		},
	},
];

> npx knip
Unused dependencies (1)
eslint-import-resolver-typescript  package.json

With the corresponding .eslintrc instead, the eslint-import-resolver-typescript dependency is correctly detected:

// .eslintrc
{
	"parser": "@typescript-eslint/parser",

	"settings": {
		"import/parsers": {
			"@typescript-eslint/parser": [".ts", ".tsx"]
		},
		"import/resolver": {
			"typescript": true,
			"node": true,
		},
	},

	"plugins": [
		"import",
		"@typescript-eslint",
	],

	"extends": [
		"eslint:recommended",
		"plugin:import/recommended",
		"plugin:import/typescript",
		"plugin:@typescript-eslint/recommended",
	],
}

[justb3a]

same here: ("knip": "5.34.0")

> knip

Unresolved imports (3)
@typescript-eslint/parser      .eslintrc.cjs
eslint-plugin-testing-library  .eslintrc.cjs
jsonc-eslint-parser            .eslintrc.cjs

[webpro]

Thanks for using Knip everyone, but please create an actual issue reproduction. Or rather, open a pull request.

It was my assumption that eslint.config.{js,cjs,mjs} didn't require any custom parsing (like .eslintrc.cjs does) and could just be an entry file, but apparently that's not the case, this config file also requires some parsing to find the used dependencies.

[webpro]

same here: ("knip": "5.34.0")

> knip

Unresolved imports (3)
@typescript-eslint/parser      .eslintrc.cjs
eslint-plugin-testing-library  .eslintrc.cjs
jsonc-eslint-parser            .eslintrc.cjs

This is a different issue, because only eslint.config.* uses the new flat config.

[guillaumebrunerie]

Thanks for using Knip everyone, but please create an actual issue reproduction. Or rather, open a pull request.

There is a actual reproduction in my comment just above.

[webpro]

Please see https://knip.dev/guides/issue-reproduction

[guillaumebrunerie]

My comment contains all of the exact commands and files needed to reproduce the issue from scratch. What more do you need?

Sure, I can run the commands again and put it on GitHub, here you go: https://github.com/guillaumebrunerie/knip-import-resolver-test

git clone https://github.com/guillaumebrunerie/knip-import-resolver-test
cd knip-import-resolver-test
npm install
npx knip

[webpro]

Not trying to be pedantic or annoying, but please understand this isn't the first issue reported and it's super helpful in understanding and getting to the root of the issue. Trust me, I did my part by developing and maintaining this tool.

[webpro]

What more do you need?

Also, this isn't about what I need.

[guillaumebrunerie]

Not trying to be pedantic or annoying, but please understand this isn't the first issue reported and it's super helpful in understanding and getting to the root of the issue. Trust me, I did my part by developing and maintaining this tool.

I was trying to be helpful by providing a reproduction starting from npm create vite and an eslint.config.js file, rather than dumping a full repository, to make it clear that it has nothing to do with other files that a repository typically contains (like tsconfig.json files and whatnot), while making it still very easy to reproduce locally from scratch.

[webpro]

I've extended the ESLint plugin for eslint.config.* files:

• Added .ts, .mts and .cts extensions to be picked up as ESLint config files
• Returning settings from flat configs (while leaving out '@typescript-eslint/parser, this is different as per the docs of typescript-eslint).

It's a basis for further development, feel free to let me know what else should be included as well.

Might open a little can of worms here, as the plugin now actually loads the eslint.config.* files (previously only statically parsed it). Would be great if you could try it out before release with something like:

npm i -D https://pkg.pr.new/knip@c6d5c10

[ronbraha]

I've extended the ESLint plugin for eslint.config.* files:

• Added .ts, .mts and .cts extensions to be picked up as ESLint config files
• Returning settings from flat configs (while leaving out '@typescript-eslint/parser, this is different as per the docs of typescript-eslint).

It's a basis for further development, feel free to let me know what else should be included as well.

Might open a little can of worms here, as the plugin now actually loads the eslint.config.* files (previously only statically parsed it). Would be great if you could try it out before release with something like:

npm i -D https://pkg.pr.new/knip@c6d5c10

Thanks! I can confirm that this solved the issue.
I will wait for an official release to upgrade

[webpro]

Thanks for confirming!

Might open a little can of worms here, as the plugin now actually loads the eslint.config.* files

Shouldn't be an issue actually, just realized ESLint itself also uses jiti for loading this file.

[guillaumebrunerie]

Works fine here too, thanks!

[webpro]

Update: there's an issue with loading eslint.config.js files, please see #818 for details.