refactor(linter/plugins): improve calculating plugin name

apps/oxlint/src-js/cli.ts

@@ -6,7 +6,7 @@ import { lint } from './bindings.js';
 let loadPlugin: typeof loadPluginWrapper | null = null;
 let lintFile: typeof lintFileWrapper | null = null;
 
-function loadPluginWrapper(path: string, packageName?: string): Promise<string> {
+function loadPluginWrapper(path: string, packageName: string | null): Promise<string> {
   if (loadPlugin === null) {
     const require = createRequire(import.meta.url);
     // `plugins.js` is in root of `dist`. See `tsdown.config.ts`.

apps/oxlint/src-js/plugins/load.ts

@@ -102,10 +102,10 @@ interface PluginDetails {
  * containing try/catch.
  *
  * @param path - Absolute path of plugin file
- * @param packageName - Optional package name from package.json (fallback if plugin.meta.name is missing)
+ * @param packageName - Optional package name from `package.json` (fallback if `plugin.meta.name` is not defined)
  * @returns JSON result
  */
-export async function loadPlugin(path: string, packageName?: string): Promise<string> {
+export async function loadPlugin(path: string, packageName: string | null): Promise<string> {
   try {
     const res = await loadPluginImpl(path, packageName);
     return JSON.stringify({ Success: res });
@@ -118,13 +118,15 @@ export async function loadPlugin(path: string, packageName?: string): Promise<st
  * Load a plugin.
  *
  * @param path - Absolute path of plugin file
- * @param packageName - Optional package name from package.json (fallback if plugin.meta.name is missing)
+ * @param packageName - Optional package name from `package.json` (fallback if `plugin.meta.name` is not defined)
  * @returns - Plugin details
  * @throws {Error} If plugin has already been registered
- * @throws {TypeError} If one of plugin's rules is malformed or its `createOnce` method returns invalid visitor
+ * @throws {Error} If plugin has no name
+ * @throws {TypeError} If one of plugin's rules is malformed, or its `createOnce` method returns invalid visitor
+ * @throws {TypeError} if `plugin.meta.name` is not a string
  * @throws {*} If plugin throws an error during import
  */
-async function loadPluginImpl(path: string, packageName?: string): Promise<PluginDetails> {
+async function loadPluginImpl(path: string, packageName: string | null): Promise<PluginDetails> {
   if (registeredPluginPaths.has(path)) {
     throw new Error('This plugin has already been registered. This is a bug in Oxlint. Please report it.');
   }
@@ -134,13 +136,9 @@ async function loadPluginImpl(path: string, packageName?: string): Promise<Plugi
   registeredPluginPaths.add(path);
 
   // TODO: Use a validation library to assert the shape of the plugin, and of rules
-  // Get plugin name from plugin.meta.name, or fall back to package name from package.json
-  const pluginName = plugin.meta?.name ?? packageName;
-  if (!pluginName) {
-    throw new TypeError(
-      'Plugin must have either meta.name or be loaded from an npm package with a name field in package.json',
-    );
-  }
+
+  const pluginName = getPluginName(plugin, packageName);
+
   const offset = registeredRules.length;
   const { rules } = plugin;
   const ruleNames = ObjectKeys(rules);
@@ -223,6 +221,35 @@ async function loadPluginImpl(path: string, packageName?: string): Promise<Plugi
   return { name: pluginName, offset, ruleNames };
 }
 
+/**
+ * Get plugin name.
+ * - If `plugin.meta.name` is defined, return it.
+ * - Otherwise, fall back to `packageName`, if defined.
+ * - If neither is defined, throw an error.
+ *
+ * @param plugin - Plugin object
+ * @param packageName - Package name from `package.json`
+ * @returns Plugin name
+ * @throws {TypeError} If `plugin.meta.name` is not a string
+ * @throws {Error} If neither `plugin.meta.name` nor `packageName` are defined
+ */
+function getPluginName(plugin: Plugin, packageName: string | null): string {
+  const pluginMeta = plugin.meta;
+  if (pluginMeta != null) {
+    const pluginMetaName = pluginMeta.name;
+    if (pluginMetaName != null) {
+      if (typeof pluginMetaName !== 'string') throw new TypeError('`plugin.meta.name` must be a string if defined');
+      return pluginMetaName;
+    }
+  }
+
+  if (packageName !== null) return packageName;
+
+  throw new Error(
+    'Plugin must either define `meta.name`, or be loaded from an NPM package with a `name` field in `package.json`',
+  );
+}
+
 /**
  * Validate and conform `before` / `after` hook function.
  * @param hookFn - Hook function, or `null` / `undefined`