test: change test runner to vitest (#525)

* test: change test runner to vitest

This change moves the test runner from `mocha` + `nyc` to `vitest`.

In order to import `vitest` the tests had to be in esm, so I checked out everything under the `tests` folder from #516 (leaving the source as it was).

I also moved the `eslint-rule-tester` out of the `tests/lib` folder and into its own `utils` folder.  That way vitest didn't treat it as a test.

Note: rather than using `vitest`'s preferred `v8` coverage reporter, I used the `istanbul` one, to ensure the coverages between old and new were the same.  I did notice that when I tried the `v8` coverage reporter, the coverage numbers were much less.  Something to consider as a follow-up change.  The v8 reporter *should* be more accurate, so the coverage may not be as high as it seems.  I'd recommend moving up to the `v8` reporter after the esm branch lands.

* test: update fixtures tsconfig to use wildcard

* build: remove `globals` and packageManager config

Author: michaelfaith

.gitignore

@@ -1,5 +1,5 @@
 .idea
-.nyc_output
+coverage
 .vscode
 node_modules/
 npm-debug.log

eslint.config.js

@@ -2,7 +2,6 @@
 
 const js = require('@eslint/js');
 const { FlatCompat } = require('@eslint/eslintrc');
-const globals = require('globals');
 const markdown = require('eslint-plugin-markdown');
 const pluginN = require('eslint-plugin-n');
 const eslintPluginConfig = require('eslint-plugin-eslint-plugin/configs/all');
@@ -54,7 +53,7 @@ module.exports = [
   },
   {
     files: ['tests/**/*.js'],
-    languageOptions: { globals: globals.mocha },
+    languageOptions: { sourceType: 'module' },
   },
   {
     files: ['**/*.md'],

package.json

@@ -18,7 +18,7 @@
     "lint:js-docs": "eslint --no-inline-config \"**/*.md\"",
     "lint:package-json": "npmPkgJsonLint .",
     "release": "release-it",
-    "test": "nyc --all --check-coverage --include lib mocha tests --recursive",
+    "test": "vitest run --coverage",
     "test:remote": "eslint-remote-tester -c ./eslint-remote-tester.config.mjs",
     "update:eslint-docs": "eslint-doc-generator"
   },
@@ -43,12 +43,6 @@
     "@eslint-community/eslint-utils": "^4.4.0",
     "estraverse": "^5.3.0"
   },
-  "nyc": {
-    "branches": 95,
-    "functions": 99,
-    "lines": 99,
-    "statements": 99
-  },
   "devDependencies": {
     "@commitlint/cli": "^19.6.0",
     "@commitlint/config-conventional": "^19.6.0",
@@ -60,7 +54,7 @@
     "@types/estree": "^1.0.8",
     "@typescript-eslint/parser": "^8.34.1",
     "@typescript-eslint/utils": "^8.34.1",
-    "chai": "^4.5.0",
+    "@vitest/coverage-istanbul": "^3.2.4",
     "eslint": "^9.16.0",
     "eslint-config-not-an-aardvark": "^2.1.0",
     "eslint-config-prettier": "^9.1.0",
@@ -73,17 +67,15 @@
     "eslint-remote-tester": "^4.0.1",
     "eslint-scope": "^8.0.1",
     "espree": "^10.0.1",
-    "globals": "^15.13.0",
     "husky": "^9.1.7",
     "lodash": "^4.17.21",
     "markdownlint-cli": "^0.43.0",
-    "mocha": "^11.0.0",
     "npm-package-json-lint": "^8.0.0",
     "npm-run-all2": "^7.0.1",
-    "nyc": "^17.1.0",
     "prettier": "^3.4.1",
     "release-it": "^17.2.0",
-    "typescript": "^5.8.3"
+    "typescript": "^5.8.3",
+    "vitest": "^3.2.4"
   },
   "peerDependencies": {
     "eslint": ">=8.23.0"

tests/lib/eslint-rule-tester.js

@@ -1,5 +1,6 @@
 {
   "compilerOptions": {
     "moduleResolution": "NodeNext"
-  }
+  },
+  "include": ["*.ts"]
 }

tests/lib/fixtures/tsconfig.json

@@ -1,7 +1,6 @@
-'use strict';
+import { assert, describe, it } from 'vitest';
 
-const assert = require('chai').assert;
-const plugin = require('../..');
+import plugin from '../../lib/index.js';
 
 const RULE_NAMES = Object.keys(plugin.rules);
 

tests/lib/index.js

@@ -1,15 +1,17 @@
-'use strict';
+import { readdirSync, readFileSync } from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
 
-const { readdirSync, readFileSync } = require('fs');
-const path = require('path');
-const assert = require('chai').assert;
-const plugin = require('../..');
+import { assert, describe, it } from 'vitest';
+
+import plugin from '../../lib/index.js';
 
 const RULE_NAMES = Object.keys(plugin.rules);
+const dirname = path.dirname(fileURLToPath(import.meta.url));
 
 describe('rule setup is correct', () => {
   it('should have a list of exported rules and rules directory that match', () => {
-    const filePath = path.join(__dirname, '..', 'lib', 'rules');
+    const filePath = path.join(dirname, '..', 'lib', 'rules');
     const files = readdirSync(filePath);
 
     assert.deepStrictEqual(
@@ -34,7 +36,7 @@ describe('rule setup is correct', () => {
 
         it('should have the right contents', () => {
           const filePath = path.join(
-            __dirname,
+            dirname,
             '..',
             '..',
             'lib',
@@ -53,7 +55,7 @@ describe('rule setup is correct', () => {
   });
 
   it('should have tests for all rules', () => {
-    const filePath = path.join(__dirname, 'rules');
+    const filePath = path.join(dirname, 'rules');
     const files = readdirSync(filePath);
 
     assert.deepStrictEqual(
@@ -65,7 +67,7 @@ describe('rule setup is correct', () => {
   });
 
   it('should have documentation for all rules', () => {
-    const filePath = path.join(__dirname, '..', '..', 'docs', 'rules');
+    const filePath = path.join(dirname, '..', '..', 'docs', 'rules');
     const files = readdirSync(filePath);
 
     assert.deepStrictEqual(

tests/lib/rule-setup.js

@@ -3,14 +3,12 @@
  * @author Teddy Katz
  */
 
-'use strict';
-
 // ------------------------------------------------------------------------------
 // Requirements
 // ------------------------------------------------------------------------------
 
-const rule = require('../../../lib/rules/consistent-output');
-const RuleTester = require('../eslint-rule-tester').RuleTester;
+import rule from '../../../lib/rules/consistent-output.js';
+import { RuleTester } from '../../utils/eslint-rule-tester.js';
 
 const ERROR = { messageId: 'missingOutput', type: 'ObjectExpression' };
 

tests/lib/rules/consistent-output.js

@@ -3,14 +3,12 @@
  * @author 薛定谔的猫<[email protected]>
  */
 
-'use strict';
-
 // ------------------------------------------------------------------------------
 // Requirements
 // ------------------------------------------------------------------------------
 
-const rule = require('../../../lib/rules/fixer-return');
-const RuleTester = require('../eslint-rule-tester').RuleTester;
+import rule from '../../../lib/rules/fixer-return.js';
+import { RuleTester } from '../../utils/eslint-rule-tester.js';
 
 // ------------------------------------------------------------------------------
 // Tests

tests/lib/rules/fixer-return.js

@@ -2,14 +2,12 @@
  * @fileoverview Enforces the order of meta properties
  */
 
-'use strict';
-
 // ------------------------------------------------------------------------------
 // Requirements
 // ------------------------------------------------------------------------------
 
-const rule = require('../../../lib/rules/meta-property-ordering');
-const RuleTester = require('../eslint-rule-tester').RuleTester;
+import rule from '../../../lib/rules/meta-property-ordering.js';
+import { RuleTester } from '../../utils/eslint-rule-tester.js';
 
 // ------------------------------------------------------------------------------
 // Tests