build: migrate prettier config to typescript and remove eslint-plugin-prettier (eslint-community#540)

* git mv prettier config

* build: migrate prettier config to typescript and remove eslint-plugin-prettier

This change moves from using `eslint-prettier-plugin` to using `eslint-config-prettier` and prettier directly for format checking.

A result of us never running prettier on the root files, is that there were some adjustments needed.  I ran prettier on the repo and have added those changes too.

Lastly, I moved the config to `typescript`.

* revert unicorn plugin update

* revert unicorn plugin update

* force latest check for setup-node

* temporarily run in sequence to find bad script

* temporarily run in sequence to find bad script

* undo temporary debug

* force latest check for setup-node

* add explicit config flag

* remove script

* add it back

* address lint violations in utils tests

Author: michaelfaith

.github/renovate.json

@@ -1,4 +1,4 @@
 {
-    "$schema": "https://docs.renovatebot.com/renovate-schema.json",
-    "extends": ["github>eslint/eslint//.github/renovate.json5"]
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": ["github>eslint/eslint//.github/renovate.json5"]
 }

.github/workflows/main.yml

@@ -32,9 +32,21 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: 'lts/*'
+          check-latest: true
       - run: npm install
       - run: npm run lint
 
+  format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 'lts/*'
+          check-latest: true
+      - run: npm install
+      - run: npm run format:check
+
   test-remote:
     name: eslint-remote-tester
     runs-on: ubuntu-latest

.markdownlint.json

@@ -1,4 +1,7 @@
 {
   "line-length": false,
-  "no-inline-html": false
+  "no-inline-html": false,
+  "no-duplicate-heading": {
+    "siblings_only": true
+  }
 }

.prettierrc.js

@@ -1,5 +1,4 @@
-The MIT License (MIT)
-=====================
+# The MIT License (MIT)
 
 Copyright © 2016 Teddy Katz
 

CHANGELOG.md

@@ -2,9 +2,11 @@ import path from 'node:path';
 import { fileURLToPath } from 'node:url';
 import js from '@eslint/js';
 import { FlatCompat } from '@eslint/eslintrc';
+import prettier from 'eslint-config-prettier/flat';
 import markdown from 'eslint-plugin-markdown';
 import pluginN from 'eslint-plugin-n';
 import tseslint from 'typescript-eslint';
+
 import eslintPlugin from './lib/index.js';
 
 const dirname = path.dirname(fileURLToPath(import.meta.url));
@@ -25,10 +27,10 @@ export default tseslint.config([
   ...compat.extends(
     'not-an-aardvark/node',
     'plugin:@eslint-community/eslint-comments/recommended',
-    'plugin:prettier/recommended',
     'plugin:unicorn/recommended',
   ),
   pluginN.configs['flat/recommended'],
+  prettier,
   {
     rules: {
       '@eslint-community/eslint-comments/no-unused-disable': 'error',

LICENSE.md

@@ -12,10 +12,12 @@
   "license": "MIT",
   "scripts": {
     "build": "tsup",
+    "format": "prettier --write .",
+    "format:check": "prettier --check .",
     "lint": "npm-run-all --continue-on-error --aggregate-output --parallel lint:*",
     "lint:docs": "markdownlint \"**/*.md\"",
     "lint:eslint-docs": "npm-run-all -s build \"update:eslint-docs -- --check\"",
-    "lint:js": "eslint --cache --ignore-pattern \"**/*.md\" .",
+    "lint:js": "eslint --cache --ignore-pattern \"**/*.md\"",
     "lint:js-docs": "eslint --no-inline-config \"**/*.md\"",
     "lint:package-json": "npmPkgJsonLint .",
     "release": "release-it",
@@ -69,7 +71,6 @@
     "eslint-doc-generator": "^2.2.2",
     "eslint-plugin-markdown": "^5.1.0",
     "eslint-plugin-n": "^17.21.0",
-    "eslint-plugin-prettier": "^5.5.3",
     "eslint-plugin-unicorn": "^56.0.1",
     "eslint-remote-tester": "^4.0.3",
     "eslint-scope": "^8.0.1",
@@ -80,7 +81,7 @@
     "markdownlint-cli": "^0.43.0",
     "npm-package-json-lint": "^8.0.0",
     "npm-run-all2": "^7.0.1",
-    "prettier": "^3.4.1",
+    "prettier": "^3.6.2",
     "release-it": "^17.2.0",
     "tsup": "^8.5.0",
     "typescript": "^5.9.2",

eslint.config.ts

@@ -0,0 +1,7 @@
+import { type Config } from 'prettier';
+
+const config: Config = {
+  singleQuote: true,
+};
+
+export default config;

package.json

@@ -1653,8 +1653,8 @@ describe('utils', () => {
     });
   });
 
-  describe('evaluateObjectProperties', function () {
-    it('behaves correctly with simple object expression', function () {
+  describe('evaluateObjectProperties', () => {
+    it('behaves correctly with simple object expression', () => {
       const getObjectExpression = (ast: Program): ObjectExpression =>
         (ast.body[0] as VariableDeclaration).declarations[0]
           .init as ObjectExpression;
@@ -1670,7 +1670,7 @@ describe('utils', () => {
       assert.deepEqual(result, getObjectExpression(ast).properties);
     });
 
-    it('behaves correctly with spreads of objects', function () {
+    it('behaves correctly with spreads of objects', () => {
       const getObjectExpression = (
         ast: Program,
         bodyElement: number,
@@ -1703,7 +1703,7 @@ describe('utils', () => {
       ]);
     });
 
-    it('behaves correctly with non-variable spreads', function () {
+    it('behaves correctly with non-variable spreads', () => {
       const getObjectExpression = (ast: Program): ObjectExpression =>
         (ast.body[1] as VariableDeclaration).declarations[0]
           .init as ObjectExpression;
@@ -1720,7 +1720,7 @@ describe('utils', () => {
       assert.deepEqual(result, []);
     });
 
-    it('behaves correctly with spread with variable that cannot be found', function () {
+    it('behaves correctly with spread with variable that cannot be found', () => {
       const ast = espree.parse(`const obj = { ...foo };`, {
         ecmaVersion: 9,
         range: true,
@@ -1734,7 +1734,7 @@ describe('utils', () => {
       assert.deepEqual(result, []);
     });
 
-    it('behaves correctly when passed wrong node type', function () {
+    it('behaves correctly when passed wrong node type', () => {
       const ast = espree.parse(`foo();`, {
         ecmaVersion: 9,
         range: true,
@@ -1745,7 +1745,7 @@ describe('utils', () => {
     });
   });
 
-  describe('getMessagesNode', function () {
+  describe('getMessagesNode', () => {
     type TestCase = {
       code: string;
       getResult: ((ast: Program) => ObjectExpression) | (() => void);
@@ -1821,7 +1821,7 @@ describe('utils', () => {
     });
   });
 
-  describe('getMessageIdNodes', function () {
+  describe('getMessageIdNodes', () => {
     type TestCase = {
       code: string;
       getResult: (ast: Program) => Property[];
@@ -1892,7 +1892,7 @@ describe('utils', () => {
     });
   });
 
-  describe('getMessageIdNodeById', function () {
+  describe('getMessageIdNodeById', () => {
     type TestCase = {
       code: string;
       run: (
@@ -1961,7 +1961,7 @@ describe('utils', () => {
     });
   });
 
-  describe('findPossibleVariableValues', function () {
+  describe('findPossibleVariableValues', () => {
     it('returns the right nodes', () => {
       const code =
         'let x = 123; x = 456; x = foo(); if (foo) { x = 789; } x(); console.log(x); x += "shouldIgnore"; x + "shouldIgnore";';
@@ -2006,7 +2006,7 @@ describe('utils', () => {
     });
   });
 
-  describe('isVariableFromParameter', function () {
+  describe('isVariableFromParameter', () => {
     it('returns true for function parameter', () => {
       const code =
         'function myFunc(x) { if (foo) { x = "abc"; } console.log(x) }; myFunc("def");';