refactor: Upgrade ESLint

conf/environments.js

@@ -23,7 +23,7 @@ function getDiff(current, prev) {
     const retv = {};
 
     for (const [key, value] of Object.entries(current)) {
-        if (!Object.hasOwnProperty.call(prev, key)) {
+        if (!Object.hasOwn(prev, key)) {
             retv[key] = value;
         }
     }

eslint.config.js

@@ -0,0 +1,76 @@
+/**
+ * @fileoverview ESLint configuration file
+ * @author Nicholas C. Zakas
+ */
+
+//-----------------------------------------------------------------------------
+// Imports
+//-----------------------------------------------------------------------------
+
+import eslintConfigESLint from "eslint-config-eslint";
+import n from "eslint-plugin-n";
+//-----------------------------------------------------------------------------
+// Config
+//-----------------------------------------------------------------------------
+
+export default [
+
+    {
+        ignores: [
+            "tests/fixtures",
+            "coverage",
+            "docs",
+            "jsdoc",
+            "dist",
+        ]
+    },
+
+    ...eslintConfigESLint,
+    {
+        plugins: {
+            n,
+        },
+        languageOptions: {
+            ecmaVersion: 2020
+        },
+
+        /*
+        * it fixes eslint-plugin-jsdoc's reports: "Invalid JSDoc tag name "template" jsdoc/check-tag-names"
+        * refs: /~https://github.com/gajus/eslint-plugin-jsdoc#check-tag-names
+        */
+        settings: {
+            jsdoc: {
+                mode: "typescript"
+            }
+        },
+    },
+    {
+        files: ["tests/**/*"],
+        languageOptions: {
+            globals: {
+                describe: "readonly",
+                xdescribe: "readonly",
+                it: "readonly",
+                xit: "readonly",
+                beforeEach: "readonly",
+                afterEach: "readonly",
+                before: "readonly",
+                after: "readonly"
+            }
+        },
+        rules: {
+            "no-restricted-syntax": ["error", {
+                selector: "CallExpression[callee.object.name='assert'][callee.property.name='doesNotThrow']",
+                message: "`assert.doesNotThrow()` should be replaced with a comment next to the code."
+            }],
+
+            // Overcome /~https://github.com/mysticatea/eslint-plugin-node/issues/250
+            "n/no-unsupported-features/es-syntax": ["error", {
+                ignores: [
+                    "modules",
+                    "dynamicImport"
+                ]
+            }]
+        }
+    }
+];

lib/cascading-config-array-factory.js

@@ -23,8 +23,8 @@
 //------------------------------------------------------------------------------
 
 import debugOrig from "debug";
-import os from "os";
-import path from "path";
+import os from "node:os";
+import path from "node:path";
 
 import { ConfigArrayFactory } from "./config-array-factory.js";
 import {
@@ -193,7 +193,7 @@ function createCLIConfigArray({
  */
 class ConfigurationNotFoundError extends Error {
 
-    // eslint-disable-next-line jsdoc/require-description
+
     /**
      * @param {string} directoryPath The directory path.
      */
@@ -345,6 +345,7 @@ class CascadingConfigArrayFactory {
      * @param {string} directoryPath The path to a leaf directory.
      * @param {boolean} configsExistInSubdirs `true` if configurations exist in subdirectories.
      * @returns {ConfigArray} The loaded config.
+     * @throws {Error} If a config file is invalid.
      * @private
      */
     _loadConfigInAncestors(directoryPath, configsExistInSubdirs = false) {
@@ -446,6 +447,7 @@ class CascadingConfigArrayFactory {
      * @param {string} directoryPath The path to the leaf directory to find config files.
      * @param {boolean} ignoreNotFoundError If `true` then it doesn't throw `ConfigurationNotFoundError`.
      * @returns {ConfigArray} The loaded config.
+     * @throws {Error} If a config file is invalid.
      * @private
      */
     _finalizeConfigArray(configArray, directoryPath, ignoreNotFoundError) {
@@ -482,7 +484,7 @@ class CascadingConfigArrayFactory {
                     !directoryPath.startsWith(homePath)
                 ) {
                     const lastElement =
-                        personalConfigArray[personalConfigArray.length - 1];
+                        personalConfigArray.at(-1);
 
                     emitDeprecationWarning(
                         lastElement.filePath,

lib/config-array-factory.js

@@ -39,10 +39,10 @@
 //------------------------------------------------------------------------------
 
 import debugOrig from "debug";
-import fs from "fs";
+import fs from "node:fs";
 import importFresh from "import-fresh";
-import { createRequire } from "module";
-import path from "path";
+import { createRequire } from "node:module";
+import path from "node:path";
 import stripComments from "strip-json-comments";
 
 import {
@@ -254,7 +254,7 @@ function loadPackageJSONConfigFile(filePath) {
     try {
         const packageData = loadJSONConfigFile(filePath);
 
-        if (!Object.hasOwnProperty.call(packageData, "eslintConfig")) {
+        if (!Object.hasOwn(packageData, "eslintConfig")) {
             throw Object.assign(
                 new Error("package.json file doesn't have 'eslintConfig' field."),
                 { code: "ESLINT_CONFIG_FIELD_NOT_FOUND" }
@@ -273,6 +273,7 @@ function loadPackageJSONConfigFile(filePath) {
  * Loads a `.eslintignore` from a file.
  * @param {string} filePath The filename to load.
  * @returns {string[]} The ignore patterns from the file.
+ * @throws {Error} If the file cannot be read.
  * @private
  */
 function loadESLintIgnoreFile(filePath) {
@@ -345,7 +346,7 @@ function loadConfigFile(filePath) {
 function writeDebugLogForLoading(request, relativeTo, filePath) {
     /* istanbul ignore next */
     if (debug.enabled) {
-        let nameAndVersion = null;
+        let nameAndVersion = null; // eslint-disable-line no-useless-assignment -- known bug in the rule
 
         try {
             const packageJsonPath = ModuleResolver.resolve(
@@ -510,6 +511,7 @@ class ConfigArrayFactory {
      * @param {Object} [options] The options.
      * @param {string} [options.basePath] The base path to resolve relative paths in `overrides[].files`, `overrides[].excludedFiles`, and `ignorePatterns`.
      * @param {string} [options.name] The config name.
+     * @throws {Error} If the config file is invalid.
      * @returns {ConfigArray} Loaded config. An empty `ConfigArray` if any config doesn't exist.
      */
     loadInDirectory(directoryPath, { basePath, name } = {}) {
@@ -595,6 +597,7 @@ class ConfigArrayFactory {
     /**
      * Load `.eslintignore` file in the current working directory.
      * @returns {ConfigArray} Loaded config. An empty `ConfigArray` if any config doesn't exist.
+     * @throws {Error} If the ignore file is invalid.
      */
     loadDefaultESLintIgnore() {
         const slots = internalSlotsMap.get(this);
@@ -607,7 +610,7 @@ class ConfigArrayFactory {
         if (fs.existsSync(packageJsonPath)) {
             const data = loadJSONConfigFile(packageJsonPath);
 
-            if (Object.hasOwnProperty.call(data, "eslintIgnore")) {
+            if (Object.hasOwn(data, "eslintIgnore")) {
                 if (!Array.isArray(data.eslintIgnore)) {
                     throw new Error("Package.json eslintIgnore property requires an array of paths");
                 }
@@ -796,6 +799,7 @@ class ConfigArrayFactory {
      * @param {string} extendName The name of a base config.
      * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
      * @returns {IterableIterator<ConfigArrayElement>} The normalized config.
+     * @throws {Error} If the extended config file can't be loaded.
      * @private
      */
     _loadExtends(extendName, ctx) {
@@ -819,6 +823,7 @@ class ConfigArrayFactory {
      * @param {string} extendName The name of a base config.
      * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
      * @returns {IterableIterator<ConfigArrayElement>} The normalized config.
+     * @throws {Error} If the extended config file can't be loaded.
      * @private
      */
     _loadExtendedBuiltInConfig(extendName, ctx) {
@@ -868,6 +873,7 @@ class ConfigArrayFactory {
      * @param {string} extendName The name of a base config.
      * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
      * @returns {IterableIterator<ConfigArrayElement>} The normalized config.
+     * @throws {Error} If the extended config file can't be loaded.
      * @private
      */
     _loadExtendedPluginConfig(extendName, ctx) {
@@ -905,6 +911,7 @@ class ConfigArrayFactory {
      * @param {string} extendName The name of a base config.
      * @param {ConfigArrayFactoryLoadingContext} ctx The loading context.
      * @returns {IterableIterator<ConfigArrayElement>} The normalized config.
+     * @throws {Error} If the extended config file can't be loaded.
      * @private
      */
     _loadExtendedShareableConfig(extendName, ctx) {

lib/config-array/config-array.js

@@ -178,6 +178,7 @@ class PluginConflictError extends Error {
  * @param {Record<string, DependentPlugin>} target The destination to merge
  * @param {Record<string, DependentPlugin>|undefined} source The source to merge.
  * @returns {void}
+ * @throws {PluginConflictError} When a plugin was conflicted.
  */
 function mergePlugins(target, source) {
     if (!isNonNullObject(source)) {
@@ -258,6 +259,7 @@ function mergeRuleConfigs(target, source) {
  * @param {ConfigArray} instance The config elements.
  * @param {number[]} indices The indices to use.
  * @returns {ExtractedConfig} The extracted config.
+ * @throws {Error} When a plugin is conflicted.
  */
 function createConfig(instance, indices) {
     const config = new ExtractedConfig();

lib/config-array/config-dependency.js

@@ -15,7 +15,7 @@
  * @author Toru Nagashima </~https://github.com/mysticatea>
  */
 
-import util from "util";
+import util from "node:util";
 
 /**
  * The class is to store parsers or plugins.
@@ -88,8 +88,8 @@ class ConfigDependency {
         this.importerPath = importerPath;
     }
 
-    // eslint-disable-next-line jsdoc/require-description
     /**
+     * Converts this instance to a JSON compatible object.
      * @returns {Object} a JSON compatible object.
      */
     toJSON() {
@@ -103,14 +103,14 @@ class ConfigDependency {
         return obj;
     }
 
-    // eslint-disable-next-line jsdoc/require-description
     /**
+     * Custom inspect method for Node.js `console.log()`.
      * @returns {Object} an object to display by `console.log()`.
      */
     [util.inspect.custom]() {
         const {
-            definition: _ignore1, // eslint-disable-line no-unused-vars
-            original: _ignore2, // eslint-disable-line no-unused-vars
+            definition: _ignore1, // eslint-disable-line no-unused-vars -- needed to make `obj` correct
+            original: _ignore2, // eslint-disable-line no-unused-vars -- needed to make `obj` correct
             ...obj
         } = this;
 

lib/config-array/extracted-config.js

@@ -120,10 +120,10 @@ class ExtractedConfig {
      */
     toCompatibleObjectAsConfigFileContent() {
         const {
-            /* eslint-disable no-unused-vars */
+            /* eslint-disable no-unused-vars -- needed to make `config` correct */
             configNameOfNoInlineConfig: _ignore1,
             processor: _ignore2,
-            /* eslint-enable no-unused-vars */
+            /* eslint-enable no-unused-vars -- needed to make `config` correct */
             ignores,
             ...config
         } = this;

lib/config-array/ignore-pattern.js

@@ -32,8 +32,8 @@
 // Requirements
 //------------------------------------------------------------------------------
 
-import assert from "assert";
-import path from "path";
+import assert from "node:assert";
+import path from "node:path";
 import ignore from "ignore";
 import debugOrig from "debug";
 
@@ -117,6 +117,9 @@ const DotPatterns = Object.freeze([".*", "!.eslintrc.*", "!../"]);
 // Public
 //------------------------------------------------------------------------------
 
+/**
+ *
+ */
 class IgnorePattern {
 
     /**
@@ -153,9 +156,7 @@ class IgnorePattern {
         debug("Create with: %o", ignorePatterns);
 
         const basePath = getCommonAncestorPath(ignorePatterns.map(p => p.basePath));
-        const patterns = [].concat(
-            ...ignorePatterns.map(p => p.getPatternsRelativeTo(basePath))
-        );
+        const patterns = ignorePatterns.flatMap(p => p.getPatternsRelativeTo(basePath));
         const ig = ignore({ allowRelativePaths: true }).add([...DotPatterns, ...patterns]);
         const dotIg = ignore({ allowRelativePaths: true }).add(patterns);