yarn.config.cjs support

packages/knip/fixtures/plugins/yarn/package.json

@@ -0,0 +1,7 @@
+{
+  "name": "@fixtures/yarn",
+  "version": "*",
+  "devDependencies": {
+    "@yarnpkg/types": "latest"
+  }
+}

packages/knip/fixtures/plugins/yarn/yarn.config.cjs

@@ -0,0 +1,10 @@
+// https://yarnpkg.com/features/constraints
+
+/** @type {import('@yarnpkg/types')} */
+const { defineConfig } = require('@yarnpkg/types');
+
+module.exports = defineConfig({
+  async constraints({Yarn}) {
+    // `Yarn` is now well-typed ✨
+  },
+});

packages/knip/fixtures/plugins/yarn/yarn.lock

@@ -0,0 +1,6 @@
+# This file is generated by running "yarn install" inside your project.
+# Manual changes might be lost - proceed with caution!
+
+__metadata:
+  version: 8
+  cacheKey: 10

packages/knip/schema.json

@@ -612,6 +612,10 @@
           "title": "xo plugin configuration (https://knip.dev/reference/plugins/xo)",
           "$ref": "#/definitions/plugin"
         },
+        "yarn": {
+          "title": "yarn plugin configuration (https://knip.dev/reference/plugins/yarn)",
+          "$ref": "#/definitions/plugin"
+        },
         "yorkie": {
           "title": "yorkie plugin configuration (https://knip.dev/reference/plugins/yorkie)",
           "$ref": "#/definitions/plugin"

packages/knip/src/plugins/index.ts

@@ -84,6 +84,7 @@ import { default as webpack } from './webpack/index.js';
 import { default as wireit } from './wireit/index.js';
 import { default as wrangler } from './wrangler/index.js';
 import { default as xo } from './xo/index.js';
+import { default as yarn } from './yarn/index.js';
 import { default as yorkie } from './yorkie/index.js';
 
 export const Plugins = {
@@ -172,5 +173,6 @@ export const Plugins = {
   wireit,
   wrangler,
   xo,
+  yarn,
   yorkie,
 };

packages/knip/src/plugins/yarn/index.ts

@@ -0,0 +1,19 @@
+import type { IsPluginEnabled, Plugin } from '../../types/config.js';
+import { _glob } from '../../util/glob.js';
+
+// https://yarnpkg.com/features/constraints
+
+const title = 'Yarn';
+
+const enablers = 'This plugin is enabled when a `yarn.lock` file is found in the root folder.';
+
+const isEnabled: IsPluginEnabled = async ({ cwd }) => (await _glob({ cwd, patterns: ['yarn.lock'] })).length > 0;
+
+const entry: string[] = ['yarn.config.cjs'];
+
+export default {
+  title,
+  enablers,
+  isEnabled,
+  entry,
+} satisfies Plugin;

packages/knip/src/schema/plugins.ts

@@ -98,5 +98,6 @@ export const pluginsSchema = z.object({
   wireit: pluginSchema,
   wrangler: pluginSchema,
   xo: pluginSchema,
+  yarn: pluginSchema,
   yorkie: pluginSchema,
 });

packages/knip/src/types/PluginNames.ts

@@ -85,6 +85,7 @@ export type PluginName =
   | 'wireit'
   | 'wrangler'
   | 'xo'
+  | 'yarn'
   | 'yorkie';
 
 export const pluginNames = [
@@ -173,5 +174,6 @@ export const pluginNames = [
   'wireit',
   'wrangler',
   'xo',
+  'yarn',
   'yorkie',
 ] as const;

packages/knip/test/plugins/yarn.test.ts

@@ -0,0 +1,23 @@
+import { test } from 'bun:test';
+import assert from 'node:assert/strict';
+import { main } from '../../src/index.js';
+import { resolve } from '../../src/util/path.js';
+import baseArguments from '../helpers/baseArguments.js';
+import baseCounters from '../helpers/baseCounters.js';
+
+const cwd = resolve('fixtures/plugins/yarn');
+
+test('Find dependencies with the yarn plugin', async () => {
+  const { issues, counters } = await main({
+    ...baseArguments,
+    cwd,
+  });
+
+  assert(issues.files.size === 0);
+
+  assert.deepEqual(counters, {
+    ...baseCounters,
+    processed: 1,
+    total: 1,
+  });
+});