From e1061c5519ebc7d9ad0457c7437787c23501e5cc Mon Sep 17 00:00:00 2001
From: Lars Kappert <lars@webpro.nl>
Date: Sun, 1 Sep 2024 09:11:20 +0200
Subject: [PATCH] Extract packages from rules in eslint plugin

---
 packages/knip/fixtures/plugins/eslint/.eslintrc.js | 9 +++++++++
 packages/knip/src/plugins/eslint/helpers.ts        | 9 +++++++--
 packages/knip/test/plugins/eslint.test.ts          | 4 +++-
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/packages/knip/fixtures/plugins/eslint/.eslintrc.js b/packages/knip/fixtures/plugins/eslint/.eslintrc.js
index dfb48e367..d3aef9977 100644
--- a/packages/knip/fixtures/plugins/eslint/.eslintrc.js
+++ b/packages/knip/fixtures/plugins/eslint/.eslintrc.js
@@ -29,4 +29,13 @@ module.exports = {
       plugins: [['@babel/plugin-proposal-decorators', { decoratorsBeforeExport: true }]],
     },
   },
+  overrides: [
+    {
+      extends: ['plugin:@org/name/typescript'],
+      rules: {
+        '@other-org/no-unused-expressions': 'error',
+        '@other-org/no-unused-vars': 'error',
+      },
+    },
+  ],
 };
diff --git a/packages/knip/src/plugins/eslint/helpers.ts b/packages/knip/src/plugins/eslint/helpers.ts
index d4903a176..06f697668 100644
--- a/packages/knip/src/plugins/eslint/helpers.ts
+++ b/packages/knip/src/plugins/eslint/helpers.ts
@@ -18,9 +18,10 @@ const getDependencies = (config: ESLintConfig | OverrideConfig) => {
     ? getDependenciesFromConfig(config.parserOptions.babelOptions)
     : [];
   const settings = config.settings ? getDependenciesFromSettings(config.settings) : [];
+  const rules = getDependenciesFromRules(config.rules);
   const overrides: string[] = config.overrides ? [config.overrides].flat().flatMap(getDependencies) : [];
 
-  return compact([...extendsSpecifiers, ...plugins, parser, ...babelDependencies, ...settings, ...overrides]);
+  return compact([...extendsSpecifiers, ...plugins, parser, ...babelDependencies, ...settings, ...rules, ...overrides]);
 };
 
 type GetDependenciesDeep = (
@@ -85,7 +86,11 @@ const resolveExtendSpecifier = (specifier: string) => {
   return resolveSpecifier(namespace, specifier);
 };
 
-// Super custom: find dependencies of specific ESLint plugins through settings
+const getDependenciesFromRules = (rules: ESLintConfig['rules'] = {}) =>
+  Object.keys(rules).flatMap(ruleKey =>
+    ruleKey.includes('/') ? [resolveSpecifier('eslint-plugin', ruleKey.split('/').slice(0, -1).join('/'))] : []
+  );
+
 const getDependenciesFromSettings = (settings: ESLintConfig['settings'] = {}) => {
   return Object.entries(settings).flatMap(([settingKey, settings]) => {
     if (settingKey === 'import/resolver') {
diff --git a/packages/knip/test/plugins/eslint.test.ts b/packages/knip/test/plugins/eslint.test.ts
index 8ccf2cbf9..0345f976b 100644
--- a/packages/knip/test/plugins/eslint.test.ts
+++ b/packages/knip/test/plugins/eslint.test.ts
@@ -33,6 +33,8 @@ test('Find dependencies with the ESLint plugin', async () => {
   assert(issues.unlisted['.eslintrc.js']['eslint-plugin-eslint-comments']);
   assert(issues.unlisted['.eslintrc.js']['eslint-plugin-eslint-plugin']);
   assert(issues.unlisted['.eslintrc.js']['eslint-plugin-import']);
+  assert(issues.unlisted['.eslintrc.js']['@org/eslint-plugin-name/typescript']);
+  assert(issues.unlisted['.eslintrc.js']['@other-org/eslint-plugin']);
 
   assert(issues.unlisted['.eslintrc.json']['@babel/plugin-syntax-import-assertions']);
   assert(issues.unlisted['.eslintrc.json']['eslint-config-airbnb']);
@@ -43,7 +45,7 @@ test('Find dependencies with the ESLint plugin', async () => {
 
   assert.deepEqual(counters, {
     ...baseCounters,
-    unlisted: 24,
+    unlisted: 26,
     processed: 4,
     total: 4,
   });