More robust loading of CJS plugins using require()

lib/package-json.ts

@@ -1,9 +1,12 @@
-import { join, resolve, extname, basename, dirname } from 'node:path';
+import { join, resolve, basename, dirname } from 'node:path';
 import { existsSync, readFileSync, readdirSync } from 'node:fs';
 import { importAbs } from './import.js';
+import { createRequire } from 'node:module';
 import type { Plugin } from './types.js';
 import type { PackageJson } from 'type-fest';
 
+const require = createRequire(import.meta.url);
+
 export function getPluginRoot(path: string) {
   return join(process.cwd(), path);
 }
@@ -23,66 +26,54 @@ function loadPackageJson(path: string): PackageJson {
 
 export async function loadPlugin(path: string): Promise<Plugin> {
   const pluginRoot = getPluginRoot(path);
-  const pluginPackageJson = loadPackageJson(path);
-
-  // Check for the entry point on the `exports` or `main` field in package.json.
-  let pluginEntryPoint;
-  const exports = pluginPackageJson.exports;
-  if (typeof exports === 'string') {
-    pluginEntryPoint = exports;
-  } else if (
-    typeof exports === 'object' &&
-    exports !== null &&
-    !Array.isArray(exports)
-  ) {
-    // Check various properties on the `exports` object.
-    // https://nodejs.org/api/packages.html#conditional-exports
-    const propertiesToCheck: (keyof PackageJson.ExportConditions)[] = [
-      '.',
-      'node',
-      'import',
-      'require',
-      'default',
-    ];
-    for (const prop of propertiesToCheck) {
-      // @ts-expect-error -- The union type for the object is causing trouble.
-      const value = exports[prop];
-      if (typeof value === 'string') {
-        pluginEntryPoint = value;
-        break;
+  try {
+    // Try require first which should work for CJS plugins.
+    return require(pluginRoot); // eslint-disable-line import/no-dynamic-require
+  } catch {
+    // Otherwise, for ESM plugins, we'll have to try to resolve the exact plugin entry point and import it.
+    const pluginPackageJson = loadPackageJson(path);
+    let pluginEntryPoint;
+    const exports = pluginPackageJson.exports;
+    if (typeof exports === 'string') {
+      pluginEntryPoint = exports;
+    } else if (
+      typeof exports === 'object' &&
+      exports !== null &&
+      !Array.isArray(exports)
+    ) {
+      // Check various properties on the `exports` object.
+      // https://nodejs.org/api/packages.html#conditional-exports
+      const propertiesToCheck: (keyof PackageJson.ExportConditions)[] = [
+        '.',
+        'node',
+        'import',
+        'require',
+        'default',
+      ];
+      for (const prop of propertiesToCheck) {
+        // @ts-expect-error -- The union type for the object is causing trouble.
+        const value = exports[prop];
+        if (typeof value === 'string') {
+          pluginEntryPoint = value;
+          break;
+        }
       }
     }
-  } else if (typeof pluginPackageJson.main === 'string') {
-    pluginEntryPoint = pluginPackageJson.main;
-  }
-
-  if (!pluginEntryPoint) {
-    pluginEntryPoint = 'index.js'; // This is the default value for the `main` field: https://docs.npmjs.com/cli/v8/configuring-npm/package-json#main
-  }
 
-  if (pluginEntryPoint.endsWith('/')) {
-    // The `main` field is allowed to specify a directory.
-    pluginEntryPoint = `${pluginEntryPoint}/index.js`;
-  }
+    if (!pluginEntryPoint) {
+      throw new Error('Unable to determine plugin entry point.');
+    }
 
-  const SUPPORTED_FILE_TYPES = ['.js', '.cjs', '.mjs'];
-  if (!SUPPORTED_FILE_TYPES.includes(extname(pluginEntryPoint))) {
-    throw new Error(
-      `Unsupported file type for plugin entry point. Current types supported: ${SUPPORTED_FILE_TYPES.join(
-        ', '
-      )}. Entry point detected: ${pluginEntryPoint}`
-    );
-  }
+    const pluginEntryPointAbs = join(pluginRoot, pluginEntryPoint);
+    if (!existsSync(pluginEntryPointAbs)) {
+      throw new Error(
+        `ESLint plugin entry point does not exist. Tried: ${pluginEntryPoint}`
+      );
+    }
 
-  const pluginEntryPointAbs = join(pluginRoot, pluginEntryPoint);
-  if (!existsSync(pluginEntryPointAbs)) {
-    throw new Error(
-      `Could not find entry point for ESLint plugin. Tried: ${pluginEntryPoint}`
-    );
+    const { default: plugin } = await importAbs(pluginEntryPointAbs);
+    return plugin;
   }
-
-  const { default: plugin } = await importAbs(pluginEntryPointAbs);
-  return plugin;
 }
 
 export function getPluginPrefix(path: string): string {

test/fixtures/cjs-config-extends/README.md

@@ -0,0 +1,17 @@
+# eslint-plugin-test
+
+## Rules
+
+<!-- begin auto-generated rules list -->
+
+💼 Configurations enabled in.\
+✅ Set in the `recommended` configuration.
+
+| Name                           | Description            | 💼 |
+| :----------------------------- | :--------------------- | :- |
+| [no-bar](docs/rules/no-bar.md) | Description of no-bar. | ✅  |
+| [no-baz](docs/rules/no-baz.md) | Description of no-baz. | ✅  |
+| [no-biz](docs/rules/no-biz.md) | Description of no-biz. | ✅  |
+| [no-foo](docs/rules/no-foo.md) | Description of no-foo. | ✅  |
+
+<!-- end auto-generated rules list -->

test/fixtures/cjs-config-extends/base-base-base-config.cjs

@@ -0,0 +1 @@
+module.exports = { rules: { 'test/no-bar': 'error' } };

test/fixtures/cjs-config-extends/base-base-config.cjs

@@ -0,0 +1 @@
+module.exports = { extends: require.resolve('./base-base-base-config.cjs') };

test/fixtures/cjs-config-extends/base-config.cjs

@@ -0,0 +1,11 @@
+module.exports = {
+  extends: [require.resolve('./base-base-config.cjs')],
+  rules: { 'test/no-foo': 'error' },
+  overrides: [
+    {
+      extends: [require.resolve('./override-config.cjs')],
+      files: ['*.js'],
+      rules: { 'test/no-baz': 'error' },
+    },
+  ],
+};

test/fixtures/cjs-config-extends/docs/rules/no-bar.md

@@ -0,0 +1,5 @@
+# Description of no-bar (`test/no-bar`)
+
+💼 This rule is enabled in the ✅ `recommended` config.
+
+<!-- end auto-generated rule header -->

test/fixtures/cjs-config-extends/docs/rules/no-baz.md

@@ -0,0 +1,5 @@
+# Description of no-baz (`test/no-baz`)
+
+💼 This rule is enabled in the ✅ `recommended` config.
+
+<!-- end auto-generated rule header -->

test/fixtures/cjs-config-extends/docs/rules/no-biz.md

@@ -0,0 +1,5 @@
+# Description of no-biz (`test/no-biz`)
+
+💼 This rule is enabled in the ✅ `recommended` config.
+
+<!-- end auto-generated rule header -->

test/fixtures/cjs-config-extends/docs/rules/no-foo.md

@@ -0,0 +1,5 @@
+# Description of no-foo (`test/no-foo`)
+
+💼 This rule is enabled in the ✅ `recommended` config.
+
+<!-- end auto-generated rule header -->

test/fixtures/cjs-config-extends/index.cjs

@@ -0,0 +1,31 @@
+module.exports = {
+  rules: {
+    'no-foo': {
+      meta: { docs: { description: 'Description of no-foo.' } },
+      create() {},
+    },
+    'no-bar': {
+      meta: { docs: { description: 'Description of no-bar.' } },
+      create() {},
+    },
+    'no-baz': {
+      meta: { docs: { description: 'Description of no-baz.' } },
+      create() {},
+    },
+    'no-biz': {
+      meta: { docs: { description: 'Description of no-biz.' } },
+      create() {},
+    },
+  },
+  configs: {
+    recommended: {
+      extends: [
+        require.resolve('./base-config.cjs'),
+        // Should ignore these since they're external:
+        'eslint:recommended',
+        'plugin:some-plugin/recommended',
+        'prettier',
+      ],
+    },
+  },
+};

test/fixtures/cjs-config-extends/override-config.cjs

@@ -0,0 +1 @@
+module.exports = { rules: { 'test/no-biz': 'error' } };

test/fixtures/cjs-config-extends/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "eslint-plugin-test",
+  "type": "commonjs"
+}

test/fixtures/cjs-main-directory/README.md

@@ -0,0 +1,8 @@
+# eslint-plugin-test
+
+<!-- begin auto-generated rules list -->
+
+| Name |
+| :--- |
+
+<!-- end auto-generated rules list -->

test/fixtures/cjs-main-directory/lib/index.cjs

@@ -0,0 +1 @@
+module.exports = { rules: {} };

test/fixtures/cjs-main-directory/package.json

@@ -0,0 +1,5 @@
+{
+  "name": "eslint-plugin-test",
+  "type": "commonjs",
+  "main": "lib/index.cjs"
+}

test/fixtures/cjs-main-file-does-not-exist/README.md

@@ -0,0 +1,2 @@
+<!-- begin auto-generated rules list -->
+<!-- end auto-generated rules list -->

test/fixtures/cjs-main-file-does-not-exist/package.json

@@ -0,0 +1,5 @@
+{
+  "name": "eslint-plugin-test",
+  "type": "commonjs",
+  "main": "index.js"
+}

test/fixtures/cjs-missing-main/README.md

@@ -0,0 +1,8 @@
+# eslint-plugin-test
+
+<!-- begin auto-generated rules list -->
+
+| Name |
+| :--- |
+
+<!-- end auto-generated rules list -->

test/fixtures/cjs-missing-main/index.cjs

@@ -0,0 +1 @@
+module.exports = { rules: {} };

test/fixtures/cjs-missing-main/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "eslint-plugin-test",
+  "type": "commonjs"
+}

test/fixtures/cjs/README.md

@@ -0,0 +1,9 @@
+# eslint-plugin-test
+
+<!-- begin auto-generated rules list -->
+
+| Name                           | Description   |
+| :----------------------------- | :------------ |
+| [no-foo](docs/rules/no-foo.md) | disallow foo. |
+
+<!-- end auto-generated rules list -->

test/fixtures/cjs/docs/rules/no-foo.md

@@ -0,0 +1,3 @@
+# Disallow foo (`test/no-foo`)
+
+<!-- end auto-generated rule header -->

test/fixtures/cjs/index.cjs

@@ -0,0 +1,8 @@
+module.exports = {
+  rules: {
+    'no-foo': {
+      meta: { docs: { description: 'disallow foo.' } },
+      create() {},
+    },
+  },
+};

test/fixtures/cjs/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "eslint-plugin-test",
+  "type": "commonjs"
+}

test/lib/__snapshots__/generate-cjs-test.ts.snap

@@ -0,0 +1,78 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`generate (cjs) basic generates the documentation 1`] = `
+"# eslint-plugin-test
+
+<!-- begin auto-generated rules list -->
+
+| Name                           | Description   |
+| :----------------------------- | :------------ |
+| [no-foo](docs/rules/no-foo.md) | disallow foo. |
+
+<!-- end auto-generated rules list -->
+"
+`;
+
+exports[`generate (cjs) basic generates the documentation 2`] = `
+"# Disallow foo (\`test/no-foo\`)
+
+<!-- end auto-generated rule header -->
+"
+`;
+
+exports[`generate (cjs) config that extends another config generates the documentation 1`] = `
+"# eslint-plugin-test
+
+## Rules
+
+<!-- begin auto-generated rules list -->
+
+💼 Configurations enabled in.\\
+✅ Set in the \`recommended\` configuration.
+
+| Name                           | Description            | 💼 |
+| :----------------------------- | :--------------------- | :- |
+| [no-bar](docs/rules/no-bar.md) | Description of no-bar. | ✅  |
+| [no-baz](docs/rules/no-baz.md) | Description of no-baz. | ✅  |
+| [no-biz](docs/rules/no-biz.md) | Description of no-biz. | ✅  |
+| [no-foo](docs/rules/no-foo.md) | Description of no-foo. | ✅  |
+
+<!-- end auto-generated rules list -->
+"
+`;
+
+exports[`generate (cjs) config that extends another config generates the documentation 2`] = `
+"# Description of no-foo (\`test/no-foo\`)
+
+💼 This rule is enabled in the ✅ \`recommended\` config.
+
+<!-- end auto-generated rule header -->
+"
+`;
+
+exports[`generate (cjs) config that extends another config generates the documentation 3`] = `
+"# Description of no-bar (\`test/no-bar\`)
+
+💼 This rule is enabled in the ✅ \`recommended\` config.
+
+<!-- end auto-generated rule header -->
+"
+`;
+
+exports[`generate (cjs) config that extends another config generates the documentation 4`] = `
+"# Description of no-baz (\`test/no-baz\`)
+
+💼 This rule is enabled in the ✅ \`recommended\` config.
+
+<!-- end auto-generated rule header -->
+"
+`;
+
+exports[`generate (cjs) config that extends another config generates the documentation 5`] = `
+"# Description of no-biz (\`test/no-biz\`)
+
+💼 This rule is enabled in the ✅ \`recommended\` config.
+
+<!-- end auto-generated rule header -->
+"
+`;