Update to eslint v9 with flat config

bin/check-dependency-version-consistency.ts

@@ -1,5 +1,5 @@
 #!/usr/bin/env node
-/* eslint node/shebang:"off" -- shebang needed so compiled code gets interpreted as JS */
+/* eslint n/hashbang:"off" -- shebang needed so compiled code gets interpreted as JS */
 
 import { run } from '../lib/cli.js';
 

eslint.config.js

@@ -0,0 +1,74 @@
+// @ts-check
+
+import js from '@eslint/js';
+import eslintPluginN from 'eslint-plugin-n';
+import eslintPluginJest from 'eslint-plugin-jest';
+import eslintPluginUnicorn from 'eslint-plugin-unicorn';
+import eslintPluginPrettierRecommended from 'eslint-plugin-prettier/recommended'; // eslint-disable-line import/extensions -- false positive
+import * as eslintPluginImport from 'eslint-plugin-import';
+import tseslint from 'typescript-eslint';
+
+export default tseslint.config(
+  // Configs:
+  js.configs.recommended,
+  eslintPluginImport.flatConfigs
+    ? eslintPluginImport.flatConfigs.recommended // TODO: use typescript config
+    : {},
+  eslintPluginJest.configs['flat/recommended'],
+  eslintPluginN.configs['flat/recommended'],
+  eslintPluginPrettierRecommended,
+  eslintPluginUnicorn.configs['flat/recommended'],
+  ...tseslint.configs.recommendedTypeChecked,
+
+  // Individual rules:
+  {
+    rules: {
+      'import/extensions': ['error', 'always'],
+      'import/no-unresolved': 'off',
+
+      'n/no-missing-import': 'off', // bug with recognizing node: prefix https://github.com/mysticatea/eslint-plugin-node/issues/275
+      'n/no-unsupported-features/es-syntax': [
+        'error',
+        { ignores: ['modules'] },
+      ],
+
+      'prettier/prettier': [
+        'error',
+        {
+          singleQuote: true,
+        },
+      ],
+
+      'unicorn/import-style': 'off',
+      'unicorn/no-useless-undefined': 'off', // We use a lot of `return undefined` to satisfy the `consistent-return` rule.
+
+      '@typescript-eslint/prefer-readonly': 'error',
+      '@typescript-eslint/require-array-sort-compare': 'error',
+    },
+
+    // typescript-eslint parser options:
+    languageOptions: {
+      parserOptions: {
+        projectService: true,
+        tsconfigRootDir: import.meta.dirname,
+      },
+    },
+  },
+
+  // Disabling type-checking for JS files:
+  {
+    files: ['**/*.js'],
+    extends: [tseslint.configs.disableTypeChecked],
+  },
+
+  // Ignore files:
+  {
+    ignores: [
+      // compiled output
+      'dist/**',
+
+      // coverage
+      'coverage/**',
+    ],
+  },
+);

jest.config.cjs → jest.config.ts

@@ -1,7 +1,7 @@
-// https://kulshekhar.github.io/ts-jest/docs/guides/esm-support/
+import type { Config } from 'jest';
 
-/** @type {import('ts-jest/dist/types').InitialOptionsTsJest} */
-module.exports = {
+// https://kulshekhar.github.io/ts-jest/docs/guides/esm-support/
+const config: Config = {
   preset: 'ts-jest/presets/default-esm',
   testEnvironment: 'node',
   testMatch: ['<rootDir>/test/**/*-test.ts'],
@@ -24,3 +24,5 @@ module.exports = {
     },
   },
 };
+
+export default config;

lib/cdvc.ts

@@ -47,7 +47,7 @@ export class CDVC {
 
   public getDependencies(): readonly Dependency[] {
     return Object.keys(this.dependencies).map((dependency) =>
-      this.getDependency(dependency)
+      this.getDependency(dependency),
     );
   }
 
@@ -72,13 +72,13 @@ export class CDVC {
 
   public get hasMismatchingDependenciesFixable(): boolean {
     return Object.values(this.dependencies).some(
-      (dep) => dep.isMismatching && dep.isFixable
+      (dep) => dep.isMismatching && dep.isFixable,
     );
   }
 
   public get hasMismatchingDependenciesNotFixable(): boolean {
     return Object.values(this.dependencies).some(
-      (dep) => dep.isMismatching && !dep.isFixable
+      (dep) => dep.isMismatching && !dep.isFixable,
     );
   }
 }

lib/check.ts

@@ -25,7 +25,7 @@ import { DEFAULT_DEP_TYPES } from './defaults.js';
  */
 export function check(
   path: string,
-  options?: Options
+  options?: Options,
 ): {
   dependencies: Dependencies;
 } {
@@ -36,8 +36,8 @@ export function check(
   ) {
     throw new Error(
       `Invalid depType provided. Choices are: ${Object.keys(
-        DEPENDENCY_TYPE
-      ).join(', ')}.`
+        DEPENDENCY_TYPE,
+      ).join(', ')}.`,
     );
   }
 
@@ -64,37 +64,37 @@ export function check(
     optionsWithDefaults.ignorePackage,
     optionsWithDefaults.ignorePackagePattern.map((s) => new RegExp(s)),
     optionsWithDefaults.ignorePath,
-    optionsWithDefaults.ignorePathPattern.map((s) => new RegExp(s))
+    optionsWithDefaults.ignorePathPattern.map((s) => new RegExp(s)),
   );
 
   const dependencies = calculateVersionsForEachDependency(
     packages,
-    optionsWithDefaults.depType.map((dt) => DEPENDENCY_TYPE[dt]) // Convert string to enum.
+    optionsWithDefaults.depType.map((dt) => DEPENDENCY_TYPE[dt]), // Convert string to enum.
   );
   const dependenciesAndVersions =
     calculateDependenciesAndVersions(dependencies);
   const dependenciesAndVersionsWithMismatches = dependenciesAndVersions.filter(
-    ({ versions }) => versions.length > 1
+    ({ versions }) => versions.length > 1,
   );
 
   // Information about all dependencies.
   const dependenciesAndVersionsWithoutIgnored = filterOutIgnoredDependencies(
     dependenciesAndVersions,
     optionsWithDefaults.ignoreDep,
-    optionsWithDefaults.ignoreDepPattern.map((s) => new RegExp(s))
+    optionsWithDefaults.ignoreDepPattern.map((s) => new RegExp(s)),
   );
 
   // Information about mismatches.
   const dependenciesAndVersionsMismatchesWithoutIgnored =
     filterOutIgnoredDependencies(
       dependenciesAndVersionsWithMismatches,
       optionsWithDefaults.ignoreDep,
-      optionsWithDefaults.ignoreDepPattern.map((s) => new RegExp(s))
+      optionsWithDefaults.ignoreDepPattern.map((s) => new RegExp(s)),
     );
   const resultsAfterFix = fixVersionsMismatching(
     packages,
     dependenciesAndVersionsMismatchesWithoutIgnored,
-    !optionsWithDefaults.fix // Do dry-run if not fixing.
+    !optionsWithDefaults.fix, // Do dry-run if not fixing.
   );
   const versionsMismatchingFixable = resultsAfterFix.fixable;
 
@@ -106,15 +106,15 @@ export function check(
           dependency,
           {
             isFixable: versionsMismatchingFixable.some(
-              (dep) => dep.dependency === dependency
+              (dep) => dep.dependency === dependency,
             ),
             isMismatching: dependenciesAndVersionsMismatchesWithoutIgnored.some(
-              (dep) => dep.dependency === dependency
+              (dep) => dep.dependency === dependency,
             ),
             versions,
           },
         ];
-      })
+      }),
     ),
   };
 }

lib/cli.ts

@@ -11,7 +11,7 @@ const __dirname = dirname(fileURLToPath(import.meta.url));
 
 function getCurrentPackageVersion(): string {
   const packageJson = JSON.parse(
-    readFileSync(join(__dirname, '..', '..', 'package.json'), 'utf8') // Relative to compiled version of this file in the dist folder.
+    readFileSync(join(__dirname, '..', '..', 'package.json'), 'utf8'), // Relative to compiled version of this file in the dist folder.
   ) as PackageJson;
   if (!packageJson.version) {
     throw new Error('Could not find package.json `version`');
@@ -25,7 +25,7 @@ function getCurrentPackageVersion(): string {
  */
 function collect(
   value: string,
-  previous: readonly string[]
+  previous: readonly string[],
 ): readonly string[] {
   return [...previous, value];
 }
@@ -36,7 +36,7 @@ function collect(
  * */
 function collectCSV(
   value: string,
-  previous: readonly string[]
+  previous: readonly string[],
 ): readonly string[] {
   return [...previous, ...value.split(',')];
 }
@@ -47,60 +47,60 @@ export function run() {
 
   program
     .description(
-      'CLI tool which checks that dependencies are on consistent versions across a monorepo / npm/pnpm/Yarn workspace.'
+      'CLI tool which checks that dependencies are on consistent versions across a monorepo / npm/pnpm/Yarn workspace.',
     )
     .version(getCurrentPackageVersion())
     .addArgument(new Argument('[path]', 'path to workspace root').default('.'))
     .option(
       '--dep-type <dependency-type>',
       `Type of dependency to check (choices: ${Object.keys(
-        DEPENDENCY_TYPE
+        DEPENDENCY_TYPE,
       ).join(', ')}) (default: ${DEFAULT_DEP_TYPES.join(
-        ', '
+        ', ',
       )}) (option can be repeated)`,
       collectCSV,
-      []
+      [],
     )
     .option(
       '--fix',
       'Whether to autofix inconsistencies (using highest version present)',
-      false
+      false,
     )
     .option(
       '--ignore-dep <dependency-name>',
       'Dependency to ignore (option can be repeated)',
       collect,
-      []
+      [],
     )
     .option(
       '--ignore-dep-pattern <dependency-name-pattern>',
       'RegExp of dependency names to ignore (option can be repeated)',
       collect,
-      []
+      [],
     )
     .option(
       '--ignore-package <package-name>',
       'Workspace package to ignore (option can be repeated)',
       collect,
-      []
+      [],
     )
     .option(
       '--ignore-package-pattern <package-name-pattern>',
       'RegExp of package names to ignore (option can be repeated)',
       collect,
-      []
+      [],
     )
     .option(
       '--ignore-path <path>',
       'Workspace-relative path of packages to ignore (option can be repeated)',
       collect,
-      []
+      [],
     )
     .option(
       '--ignore-path-pattern <path-pattern>',
       'RegExp of workspace-relative path of packages to ignore (option can be repeated)',
       collect,
-      []
+      [],
     )
     .action((path: string, options: Options) => {
       const cdvc = new CDVC(path, options);