diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 1ad441b9..ba8e922f 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -12,10 +12,9 @@ jobs:
       fail-fast: false
       matrix:
         node-version:
+          - 21
           - 20
           - 18
-          - 16
-          - 14
         os:
           - ubuntu-latest
     steps:
@@ -23,7 +22,7 @@ jobs:
       - uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
-      - run: npm install
+      - run: npm install --force # ts-eslint does not support eslint v9 yet.
       - run: npm test
 
   lint:
@@ -32,18 +31,29 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: "18.x"
-      - run: npm install
+          node-version: "lts/*"
+      - run: npm install --force # ts-eslint does not support eslint v9 yet.
       - run: npm run lint
 
-  eslint7:
+  eslint8:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
     - uses: actions/setup-node@v4
       with:
-        node-version: "18.x"
-    - run: npm install
-    - run: npm install --save-dev eslint@7
+        node-version: "lts/*"
+    - run: npm install --force # ts-eslint does not support eslint v9 yet.
+    - run: npm install --save-dev eslint@8
     - run: npm test
 
+  test-remote:
+    name: eslint-remote-tester
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "lts/*"
+      - run: npm install --force # ts-eslint does not support eslint v9 yet.
+      - run: npm install --save-dev eslint@8 # eslint-remote-tester does not support eslint v9.
+      - run: npm run test:remote
diff --git a/lib/rules/no-unused-placeholders.js b/lib/rules/no-unused-placeholders.js
index edace9c3..da116ceb 100644
--- a/lib/rules/no-unused-placeholders.js
+++ b/lib/rules/no-unused-placeholders.js
@@ -101,9 +101,12 @@ module.exports = {
               const PLACEHOLDER_MATCHER = /{{\s*([^{}]+?)\s*}}/g;
               const placeholdersInMessage = new Set();
 
-              messageValue.replace(PLACEHOLDER_MATCHER, (fullMatch, term) => {
-                placeholdersInMessage.add(term);
-              });
+              messageValue.replaceAll(
+                PLACEHOLDER_MATCHER,
+                (fullMatch, term) => {
+                  placeholdersInMessage.add(term);
+                }
+              );
 
               data.properties.forEach((prop) => {
                 const key = utils.getKeyName(prop);
diff --git a/lib/rules/require-meta-docs-url.js b/lib/rules/require-meta-docs-url.js
index d52f1984..8b6f25ac 100644
--- a/lib/rules/require-meta-docs-url.js
+++ b/lib/rules/require-meta-docs-url.js
@@ -62,7 +62,7 @@ module.exports = {
     const expectedUrl =
       !options.pattern || !ruleName
         ? undefined
-        : options.pattern.replace(/{{\s*name\s*}}/g, ruleName);
+        : options.pattern.replaceAll(/{{\s*name\s*}}/g, ruleName);
 
     /**
      * Check whether a given URL is the expected URL.
diff --git a/lib/utils.js b/lib/utils.js
index c1be12c2..9a409a5b 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -719,7 +719,7 @@ module.exports = {
       return fixer.replaceText(node, `{\n${propertyText}\n}`);
     }
     return fixer.insertTextAfter(
-      sourceCode.getLastToken(node.properties[node.properties.length - 1]),
+      sourceCode.getLastToken(node.properties.at(-1)),
       `,\n${propertyText}`
     );
   },
diff --git a/package.json b/package.json
index 839a723b..2e122386 100644
--- a/package.json
+++ b/package.json
@@ -17,9 +17,9 @@
     "lint:js": "eslint --cache --ignore-pattern \"**/*.md\" .",
     "lint:js-docs": "eslint --no-inline-config \"**/*.md\"",
     "lint:package-json": "npmPkgJsonLint .",
-    "lint:remote": "eslint-remote-tester",
     "release": "release-it",
     "test": "nyc --all --check-coverage --include lib mocha tests --recursive",
+    "test:remote": "eslint-remote-tester",
     "update:eslint-docs": "eslint-doc-generator"
   },
   "files": [
@@ -52,29 +52,29 @@
   "devDependencies": {
     "@commitlint/cli": "^17.1.2",
     "@commitlint/config-conventional": "^17.1.0",
-    "@eslint/eslintrc": "^2.0.2",
-    "@eslint/js": "^8.57.0",
+    "@eslint/eslintrc": "^3.0.2",
+    "@eslint/js": "^9.0.0",
     "@release-it/conventional-changelog": "^4.3.0",
-    "@types/eslint": "^8.56.6",
+    "@types/eslint": "^8.56.7",
     "@types/estree": "^1.0.5",
-    "@typescript-eslint/parser": "^5.62.0",
-    "@typescript-eslint/utils": "^5.62.0",
+    "@typescript-eslint/parser": "^7.5.0",
+    "@typescript-eslint/utils": "^7.5.0",
     "chai": "^4.3.6",
     "dirty-chai": "^2.0.1",
-    "eslint": "^8.57.0",
+    "eslint": "^9.0.0",
     "eslint-config-not-an-aardvark": "^2.1.0",
     "eslint-config-prettier": "^8.5.0",
     "eslint-doc-generator": "^1.7.0",
     "eslint-plugin-eslint-comments": "^3.2.0",
     "eslint-plugin-eslint-plugin": "file:./",
     "eslint-plugin-markdown": "^3.0.0",
-    "eslint-plugin-n": "^16.6.2",
+    "eslint-plugin-n": "^17.0.0",
     "eslint-plugin-prettier": "^4.2.1",
-    "eslint-plugin-unicorn": "^46.0.0",
+    "eslint-plugin-unicorn": "^52.0.0",
     "eslint-remote-tester": "^3.0.1",
-    "eslint-scope": "^7.1.1",
-    "espree": "^9.4.0",
-    "globals": "^13.20.0",
+    "eslint-scope": "^8.0.1",
+    "espree": "^10.0.1",
+    "globals": "^15.0.0",
     "husky": "^8.0.1",
     "lodash": "^4.17.21",
     "markdownlint-cli": "^0.39.0",
@@ -87,10 +87,10 @@
     "typescript": "^5.4.3"
   },
   "peerDependencies": {
-    "eslint": ">=7.0.0"
+    "eslint": ">=8.23.0"
   },
   "engines": {
-    "node": "^14.17.0 || ^16.0.0 || >= 18.0.0"
+    "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
   },
   "release-it": {
     "git": {
diff --git a/tests/lib/eslint-rule-tester.js b/tests/lib/eslint-rule-tester.js
new file mode 100644
index 00000000..dd16a8e2
--- /dev/null
+++ b/tests/lib/eslint-rule-tester.js
@@ -0,0 +1,15 @@
+/**
+ * @fileoverview Helpers for tests.
+ * @author 唯然<weiran.zsd@outlook.com>
+ */
+
+'use strict';
+
+const eslintVersion = require('eslint/package.json').version;
+const { RuleTester } = require('eslint');
+const { FlatRuleTester } = require('eslint/use-at-your-own-risk');
+
+// greater than or equal to ESLint v9
+exports.gteEslintV9 = +eslintVersion.split('.')[0] >= 9;
+
+exports.RuleTester = exports.gteEslintV9 ? RuleTester : FlatRuleTester;
diff --git a/tests/lib/rules/consistent-output.js b/tests/lib/rules/consistent-output.js
index 844fde15..75ecabe8 100644
--- a/tests/lib/rules/consistent-output.js
+++ b/tests/lib/rules/consistent-output.js
@@ -10,7 +10,7 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/consistent-output');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 const ERROR = { messageId: 'missingOutput', type: 'ObjectExpression' };
 
@@ -18,7 +18,9 @@ const ERROR = { messageId: 'missingOutput', type: 'ObjectExpression' };
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester();
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('consistent-output', rule, {
   valid: [
     `
diff --git a/tests/lib/rules/fixer-return.js b/tests/lib/rules/fixer-return.js
index 62f66fb8..349a9bf4 100644
--- a/tests/lib/rules/fixer-return.js
+++ b/tests/lib/rules/fixer-return.js
@@ -10,13 +10,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/fixer-return');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('fixer-return', rule, {
   valid: [
     `
diff --git a/tests/lib/rules/meta-property-ordering.js b/tests/lib/rules/meta-property-ordering.js
index 830371fd..e5e8bce4 100644
--- a/tests/lib/rules/meta-property-ordering.js
+++ b/tests/lib/rules/meta-property-ordering.js
@@ -9,13 +9,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/meta-property-ordering');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('test-case-property-ordering', rule, {
   valid: [
     `
@@ -31,7 +33,7 @@ ruleTester.run('test-case-property-ordering', rule, {
           meta: {type, docs, fixable, schema, messages},
           create() {},
         };`,
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
 
     `
@@ -124,13 +126,13 @@ ruleTester.run('test-case-property-ordering', rule, {
           },
           create() {},
         };`,
-      parserOptions: { sourceType: 'module' },
       errors: [
         {
           messageId: 'inconsistentOrder',
           data: { order: ['type', 'docs', 'fixable'].join(', ') },
         },
       ],
+      languageOptions: { sourceType: 'module' },
     },
     {
       code: `
diff --git a/tests/lib/rules/no-deprecated-context-methods.js b/tests/lib/rules/no-deprecated-context-methods.js
index b325b9ae..84770ccd 100644
--- a/tests/lib/rules/no-deprecated-context-methods.js
+++ b/tests/lib/rules/no-deprecated-context-methods.js
@@ -10,13 +10,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/no-deprecated-context-methods');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('no-deprecated-context-methods', rule, {
   valid: [
     `
diff --git a/tests/lib/rules/no-deprecated-report-api.js b/tests/lib/rules/no-deprecated-report-api.js
index e409b9a0..6483fbde 100644
--- a/tests/lib/rules/no-deprecated-report-api.js
+++ b/tests/lib/rules/no-deprecated-report-api.js
@@ -10,13 +10,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/no-deprecated-report-api');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('no-deprecated-report-api', rule, {
   valid: [
     `
diff --git a/tests/lib/rules/no-identical-tests.js b/tests/lib/rules/no-identical-tests.js
index 0e15d1b4..6bcf4419 100644
--- a/tests/lib/rules/no-identical-tests.js
+++ b/tests/lib/rules/no-identical-tests.js
@@ -10,7 +10,7 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/no-identical-tests');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 const ERROR_OBJECT_TEST = { messageId: 'identical', type: 'ObjectExpression' };
 const ERROR_STRING_TEST = { messageId: 'identical', type: 'Literal' };
@@ -19,7 +19,9 @@ const ERROR_STRING_TEST = { messageId: 'identical', type: 'Literal' };
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester();
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('no-identical-tests', rule, {
   valid: [
     `
@@ -232,8 +234,8 @@ ruleTester.run('no-identical-tests', rule, {
           });
         }
       `,
-      parserOptions: { ecmaVersion: 2015 },
       errors: [{ messageId: 'identical', type: 'TemplateLiteral' }],
+      languageOptions: { ecmaVersion: 2015 },
     },
   ],
 });
diff --git a/tests/lib/rules/no-missing-message-ids.js b/tests/lib/rules/no-missing-message-ids.js
index 6b43a7d6..e8e2df0e 100644
--- a/tests/lib/rules/no-missing-message-ids.js
+++ b/tests/lib/rules/no-missing-message-ids.js
@@ -5,13 +5,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/no-missing-message-ids');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 9 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 
 ruleTester.run('no-missing-message-ids', rule, {
   valid: [
@@ -75,7 +77,7 @@ ruleTester.run('no-missing-message-ids', rule, {
           }
         };
       `,
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     // unrelated function 1
     `
@@ -321,7 +323,6 @@ ruleTester.run('no-missing-message-ids', rule, {
           }
         };
       `,
-      parserOptions: { sourceType: 'module' },
       errors: [
         {
           messageId: 'missingMessage',
@@ -329,6 +330,7 @@ ruleTester.run('no-missing-message-ids', rule, {
           type: 'Literal',
         },
       ],
+      languageOptions: { sourceType: 'module' },
     },
     {
       // Helper function with messageId parameter, inside rule, with missing messageId due to parameter reassignment.
diff --git a/tests/lib/rules/no-missing-placeholders.js b/tests/lib/rules/no-missing-placeholders.js
index 858fa232..56e4cf6e 100644
--- a/tests/lib/rules/no-missing-placeholders.js
+++ b/tests/lib/rules/no-missing-placeholders.js
@@ -10,7 +10,7 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/no-missing-placeholders');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 /**
  * Create an error for the given key
@@ -29,7 +29,9 @@ function error(missingKey, type, extra) {
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('no-missing-placeholders', rule, {
   valid: [
     `
diff --git a/tests/lib/rules/no-only-tests.js b/tests/lib/rules/no-only-tests.js
index 29882439..0df7e600 100644
--- a/tests/lib/rules/no-only-tests.js
+++ b/tests/lib/rules/no-only-tests.js
@@ -5,19 +5,21 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/no-only-tests');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 'latest' } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('no-only-tests', rule, {
   valid: [
     // No test cases with `only`
     `
       const { RuleTester } = require('eslint');
-      const ruleTester = new RuleTester();
+      const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
       ruleTester.run('foo', bar, {
         valid: [
           'foo',
@@ -34,7 +36,7 @@ ruleTester.run('no-only-tests', rule, {
     // `only` set to `false`
     `
       const { RuleTester } = require('eslint');
-      const ruleTester = new RuleTester();
+      const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
       ruleTester.run('foo', bar, {
         valid: [
           { code: 'foo', only: false },
@@ -61,7 +63,7 @@ ruleTester.run('no-only-tests', rule, {
       // Valid test case with `only`
       code: `
         const { RuleTester } = require('eslint');
-        const ruleTester = new RuleTester();
+        const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
         ruleTester.run('foo', bar, {
           valid: [
             { code: 'foo', only: true },
@@ -82,7 +84,7 @@ ruleTester.run('no-only-tests', rule, {
               messageId: 'removeOnly',
               output: `
         const { RuleTester } = require('eslint');
-        const ruleTester = new RuleTester();
+        const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
         ruleTester.run('foo', bar, {
           valid: [
             { code: 'foo'  },
@@ -98,7 +100,7 @@ ruleTester.run('no-only-tests', rule, {
       // Invalid test case with `only` (property at end of object, no trailing comma)
       code: `
         const { RuleTester } = require('eslint');
-        const ruleTester = new RuleTester();
+        const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
         ruleTester.run('foo', bar, {
           valid: [],
           invalid: [
@@ -119,7 +121,7 @@ ruleTester.run('no-only-tests', rule, {
               messageId: 'removeOnly',
               output: `
         const { RuleTester } = require('eslint');
-        const ruleTester = new RuleTester();
+        const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
         ruleTester.run('foo', bar, {
           valid: [],
           invalid: [
@@ -135,7 +137,7 @@ ruleTester.run('no-only-tests', rule, {
       // Invalid test case with `only` (property at end of object, with trailing comma)
       code: `
         const { RuleTester } = require('eslint');
-        const ruleTester = new RuleTester();
+        const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
         ruleTester.run('foo', bar, {
           valid: [],
           invalid: [
@@ -156,7 +158,7 @@ ruleTester.run('no-only-tests', rule, {
               messageId: 'removeOnly',
               output: `
         const { RuleTester } = require('eslint');
-        const ruleTester = new RuleTester();
+        const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
         ruleTester.run('foo', bar, {
           valid: [],
           invalid: [
@@ -172,7 +174,7 @@ ruleTester.run('no-only-tests', rule, {
       // Invalid test case with `only` (property in middle of object)
       code: `
         const { RuleTester } = require('eslint');
-        const ruleTester = new RuleTester();
+        const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
         ruleTester.run('foo', bar, {
           valid: [],
           invalid: [
@@ -193,7 +195,7 @@ ruleTester.run('no-only-tests', rule, {
               messageId: 'removeOnly',
               output: `
         const { RuleTester } = require('eslint');
-        const ruleTester = new RuleTester();
+        const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
         ruleTester.run('foo', bar, {
           valid: [],
           invalid: [
@@ -209,7 +211,7 @@ ruleTester.run('no-only-tests', rule, {
       // Invalid test case with `only` (property at beginning of object)
       code: `
         const { RuleTester } = require('eslint');
-        const ruleTester = new RuleTester();
+        const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
         ruleTester.run('foo', bar, {
           valid: [],
           invalid: [
@@ -230,7 +232,7 @@ ruleTester.run('no-only-tests', rule, {
               messageId: 'removeOnly',
               output: `
         const { RuleTester } = require('eslint');
-        const ruleTester = new RuleTester();
+        const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
         ruleTester.run('foo', bar, {
           valid: [],
           invalid: [
@@ -247,7 +249,7 @@ ruleTester.run('no-only-tests', rule, {
       // Valid test case using `RuleTester.only`
       code: `
         const { RuleTester } = require('eslint');
-        const ruleTester = new RuleTester();
+        const ruleTester = new RuleTester({languageOptions: {sourceType: "commonjs"}});
         new RuleTester().run('foo', bar, {
           valid: [
             RuleTester.only('foo'),
diff --git a/tests/lib/rules/no-property-in-node.js b/tests/lib/rules/no-property-in-node.js
index 39e4587f..bc5387c1 100644
--- a/tests/lib/rules/no-property-in-node.js
+++ b/tests/lib/rules/no-property-in-node.js
@@ -1,14 +1,16 @@
 'use strict';
 
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 const path = require('path');
 const rule = require('../../../lib/rules/no-property-in-node');
 
 const ruleTester = new RuleTester({
-  parser: require.resolve('@typescript-eslint/parser'),
-  parserOptions: {
-    project: './tsconfig.json',
-    tsconfigRootDir: path.join(__dirname, '../fixtures'),
+  languageOptions: {
+    parser: require('@typescript-eslint/parser'),
+    parserOptions: {
+      project: './tsconfig.json',
+      tsconfigRootDir: path.join(__dirname, '../fixtures'),
+    },
   },
 });
 
diff --git a/tests/lib/rules/no-unused-message-ids.js b/tests/lib/rules/no-unused-message-ids.js
index 82f9df8f..ea7b724e 100644
--- a/tests/lib/rules/no-unused-message-ids.js
+++ b/tests/lib/rules/no-unused-message-ids.js
@@ -5,13 +5,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/no-unused-message-ids');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 9 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 
 ruleTester.run('no-unused-message-ids', rule, {
   valid: [
@@ -51,7 +53,7 @@ ruleTester.run('no-unused-message-ids', rule, {
           }
         };
       `,
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     // unrelated function 1
     `
@@ -323,7 +325,6 @@ ruleTester.run('no-unused-message-ids', rule, {
           }
         };
       `,
-      parserOptions: { sourceType: 'module' },
       errors: [
         {
           messageId: 'unusedMessage',
@@ -331,6 +332,7 @@ ruleTester.run('no-unused-message-ids', rule, {
           type: 'Property',
         },
       ],
+      languageOptions: { sourceType: 'module' },
     },
     {
       // `meta` / `create` in variables
diff --git a/tests/lib/rules/no-unused-placeholders.js b/tests/lib/rules/no-unused-placeholders.js
index a57a4274..d61fd030 100644
--- a/tests/lib/rules/no-unused-placeholders.js
+++ b/tests/lib/rules/no-unused-placeholders.js
@@ -10,7 +10,7 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/no-unused-placeholders');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 /**
  * Create an error for the given key
@@ -29,7 +29,9 @@ function error(unusedKey, extra) {
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('no-unused-placeholders', rule, {
   valid: [
     `
diff --git a/tests/lib/rules/no-useless-token-range.js b/tests/lib/rules/no-useless-token-range.js
index 1ef59734..52d216a5 100644
--- a/tests/lib/rules/no-useless-token-range.js
+++ b/tests/lib/rules/no-useless-token-range.js
@@ -10,7 +10,7 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/no-useless-token-range');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 /**
  * Wraps a code sample as an eslint rule
@@ -78,7 +78,9 @@ const INVALID_CASES = [
   })
 );
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('no-useless-token-range', rule, {
   valid: [
     ...[
diff --git a/tests/lib/rules/prefer-message-ids.js b/tests/lib/rules/prefer-message-ids.js
index 34a2ac23..4f01f5b1 100644
--- a/tests/lib/rules/prefer-message-ids.js
+++ b/tests/lib/rules/prefer-message-ids.js
@@ -5,13 +5,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/prefer-message-ids');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 
 ruleTester.run('prefer-message-ids', rule, {
   valid: [
@@ -50,7 +52,7 @@ ruleTester.run('prefer-message-ids', rule, {
           }
         };
       `,
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     `
       module.exports = {
@@ -159,8 +161,8 @@ ruleTester.run('prefer-message-ids', rule, {
           }
         };
       `,
-      parserOptions: { sourceType: 'module' },
       errors: [{ messageId: 'foundMessage', type: 'Property' }],
+      languageOptions: { sourceType: 'module' },
     },
     {
       // With message in variable.
diff --git a/tests/lib/rules/prefer-object-rule.js b/tests/lib/rules/prefer-object-rule.js
index 4b7bd7de..fbc4fa50 100644
--- a/tests/lib/rules/prefer-object-rule.js
+++ b/tests/lib/rules/prefer-object-rule.js
@@ -9,13 +9,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/prefer-object-rule');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('prefer-object-rule', rule, {
   valid: [
     `
@@ -77,7 +79,7 @@ ruleTester.run('prefer-object-rule', rule, {
           },
         };
       `,
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     'module.exports = {};', // No rule.
   ],
@@ -141,27 +143,27 @@ ruleTester.run('prefer-object-rule', rule, {
           return { Program() { context.report() } };
         }};
       `,
-      parserOptions: { sourceType: 'module' },
       errors: [{ messageId: 'preferObject', line: 2, column: 24 }],
+      languageOptions: { sourceType: 'module' },
     },
     {
       code: 'export default function create(context) { return {}; };',
       output: 'export default {create(context) { return {}; }};',
-      parserOptions: { sourceType: 'module' },
       errors: [{ messageId: 'preferObject', line: 1, column: 16 }],
+      languageOptions: { sourceType: 'module' },
     },
     {
       code: 'export default (context) => { return {}; };',
       output: 'export default {create: (context) => { return {}; }};',
-      parserOptions: { sourceType: 'module' },
       errors: [{ messageId: 'preferObject', line: 1, column: 16 }],
+      languageOptions: { sourceType: 'module' },
     },
     {
       code: 'const rule = (context) => { return {}; }; export default rule;',
       output:
         'const rule = {create: (context) => { return {}; }}; export default rule;',
-      parserOptions: { sourceType: 'module' },
       errors: [{ messageId: 'preferObject', line: 1, column: 14 }],
+      languageOptions: { sourceType: 'module' },
     },
   ],
 });
diff --git a/tests/lib/rules/prefer-output-null.js b/tests/lib/rules/prefer-output-null.js
index 8fe57bcc..b7c0eda1 100644
--- a/tests/lib/rules/prefer-output-null.js
+++ b/tests/lib/rules/prefer-output-null.js
@@ -10,7 +10,7 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/prefer-output-null');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 const ERROR = { messageId: 'useOutputNull', type: 'Property' };
 
@@ -18,7 +18,9 @@ const ERROR = { messageId: 'useOutputNull', type: 'Property' };
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 'latest' } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('prefer-output-null', rule, {
   valid: [
     `
diff --git a/tests/lib/rules/prefer-placeholders.js b/tests/lib/rules/prefer-placeholders.js
index a2a3ca4f..f7fe49e0 100644
--- a/tests/lib/rules/prefer-placeholders.js
+++ b/tests/lib/rules/prefer-placeholders.js
@@ -10,13 +10,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/prefer-placeholders');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 
 ruleTester.run('prefer-placeholders', rule, {
   valid: [
diff --git a/tests/lib/rules/prefer-replace-text.js b/tests/lib/rules/prefer-replace-text.js
index 08a779c8..c83a9559 100644
--- a/tests/lib/rules/prefer-replace-text.js
+++ b/tests/lib/rules/prefer-replace-text.js
@@ -10,13 +10,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/prefer-replace-text');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 
 ruleTester.run('prefer-placeholders', rule, {
   valid: [
diff --git a/tests/lib/rules/report-message-format.js b/tests/lib/rules/report-message-format.js
index 1f086ce1..155f4c46 100644
--- a/tests/lib/rules/report-message-format.js
+++ b/tests/lib/rules/report-message-format.js
@@ -10,13 +10,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/report-message-format');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('report-message-format', rule, {
   valid: [
     // with no configuration, everything is allowed
@@ -41,7 +43,7 @@ ruleTester.run('report-message-format', rule, {
         };
       `,
       options: ['foo'],
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     {
       // With message as variable.
@@ -218,7 +220,7 @@ ruleTester.run('report-message-format', rule, {
         };
       `,
       options: ['foo'],
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     {
       // With message as variable.
diff --git a/tests/lib/rules/require-meta-docs-description.js b/tests/lib/rules/require-meta-docs-description.js
index 716eaa84..721cd626 100644
--- a/tests/lib/rules/require-meta-docs-description.js
+++ b/tests/lib/rules/require-meta-docs-description.js
@@ -5,13 +5,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/require-meta-docs-description');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 9 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('require-meta-docs-description', rule, {
   valid: [
     'foo()', // No rule.
@@ -30,7 +32,7 @@ ruleTester.run('require-meta-docs-description', rule, {
           create(context) {}
         };
       `,
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     `
       module.exports = {
@@ -157,8 +159,8 @@ ruleTester.run('require-meta-docs-description', rule, {
         };
       `,
       output: null,
-      parserOptions: { sourceType: 'module' },
       errors: [{ messageId: 'missing', type: 'ObjectExpression' }],
+      languageOptions: { sourceType: 'module' },
     },
     {
       code: `
@@ -294,8 +296,10 @@ ruleTester.run('require-meta-docs-description', rule, {
 });
 
 const ruleTesterTypeScript = new RuleTester({
-  parserOptions: { sourceType: 'module' },
-  parser: require.resolve('@typescript-eslint/parser'),
+  languageOptions: {
+    sourceType: 'module',
+    parser: require('@typescript-eslint/parser'),
+  },
 });
 ruleTesterTypeScript.run('require-meta-docs-description (TypeScript)', rule, {
   valid: [
diff --git a/tests/lib/rules/require-meta-docs-url.js b/tests/lib/rules/require-meta-docs-url.js
index a6ba0f52..9d29b177 100644
--- a/tests/lib/rules/require-meta-docs-url.js
+++ b/tests/lib/rules/require-meta-docs-url.js
@@ -10,7 +10,7 @@
 // Requirements
 // -----------------------------------------------------------------------------
 
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 const rule = require('../../../lib/rules/require-meta-docs-url');
 
 // -----------------------------------------------------------------------------
@@ -18,8 +18,8 @@ const rule = require('../../../lib/rules/require-meta-docs-url');
 // -----------------------------------------------------------------------------
 
 const tester = new RuleTester({
-  parserOptions: {
-    ecmaVersion: 2020,
+  languageOptions: {
+    sourceType: 'commonjs',
   },
 });
 
@@ -96,7 +96,7 @@ tester.run('require-meta-docs-url', rule, {
           pattern: 'path/to/{{name}}.md',
         },
       ],
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     {
       // TypeScript
@@ -108,7 +108,7 @@ tester.run('require-meta-docs-url', rule, {
         }
       `,
       options: [{ pattern: 'path/to/{{name}}.md' }],
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     {
       // `url` in variable.
@@ -733,8 +733,8 @@ url: "plugin-name/test.md"
           pattern: 'plugin-name/{{ name }}.md',
         },
       ],
-      parserOptions: { sourceType: 'module' },
       errors: [{ messageId: 'missing', type: 'ObjectExpression' }],
+      languageOptions: { sourceType: 'module' },
     },
     {
       // TypeScript
@@ -756,8 +756,8 @@ url: "plugin-name/test.md"
         }
       `,
       options: [{ pattern: 'plugin-name/{{ name }}.md' }],
-      parserOptions: { sourceType: 'module' },
       errors: [{ messageId: 'missing', type: 'ObjectExpression' }],
+      languageOptions: { sourceType: 'module' },
     },
     {
       filename: 'test.js',
diff --git a/tests/lib/rules/require-meta-fixable.js b/tests/lib/rules/require-meta-fixable.js
index 496d2134..dfc7d7ff 100644
--- a/tests/lib/rules/require-meta-fixable.js
+++ b/tests/lib/rules/require-meta-fixable.js
@@ -10,13 +10,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/require-meta-fixable');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 9 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('require-meta-fixable', rule, {
   valid: [
     // No `meta`.
@@ -50,7 +52,7 @@ ruleTester.run('require-meta-fixable', rule, {
           }
         };
       `,
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     // Value in variable.
     `
@@ -138,7 +140,7 @@ ruleTester.run('require-meta-fixable', rule, {
           create(context) { context.report(node, message, data, fix); }
         };
       `,
-      parserOptions: {
+      languageOptions: {
         ecmaVersion: 9,
       },
     },
@@ -251,8 +253,8 @@ ruleTester.run('require-meta-fixable', rule, {
           create(context) { context.report({node, message, fix: foo}); }
         };
       `,
-      parserOptions: { sourceType: 'module' },
       errors: [{ messageId: 'missing', type: 'ObjectExpression' }],
+      languageOptions: { sourceType: 'module' },
     },
     {
       code: `
diff --git a/tests/lib/rules/require-meta-has-suggestions.js b/tests/lib/rules/require-meta-has-suggestions.js
index 69451350..3a96ea59 100644
--- a/tests/lib/rules/require-meta-has-suggestions.js
+++ b/tests/lib/rules/require-meta-has-suggestions.js
@@ -5,13 +5,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/require-meta-has-suggestions');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 9 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('require-meta-has-suggestions', rule, {
   valid: [
     'module.exports = context => { return {}; };',
@@ -122,7 +124,7 @@ ruleTester.run('require-meta-has-suggestions', rule, {
           }
         };
       `,
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     // Provides suggestions, has hasSuggestions property (as variable).
     `
@@ -215,7 +217,7 @@ ruleTester.run('require-meta-has-suggestions', rule, {
           create(context) { context.report(node, message, data, fix); }
         };
       `,
-      parserOptions: {
+      languageOptions: {
         ecmaVersion: 9,
       },
     },
@@ -289,7 +291,6 @@ ruleTester.run('require-meta-has-suggestions', rule, {
         };
       `,
       output: null,
-      parserOptions: { sourceType: 'module' },
       errors: [
         {
           messageId: 'shouldBeSuggestable',
@@ -300,6 +301,7 @@ ruleTester.run('require-meta-has-suggestions', rule, {
           endColumn: 78,
         },
       ],
+      languageOptions: { sourceType: 'module' },
     },
     {
       // Reports suggestions, no hasSuggestions property, violation should be on `meta` object, empty meta object.
diff --git a/tests/lib/rules/require-meta-schema.js b/tests/lib/rules/require-meta-schema.js
index ca11074e..8903d1fd 100644
--- a/tests/lib/rules/require-meta-schema.js
+++ b/tests/lib/rules/require-meta-schema.js
@@ -5,13 +5,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/require-meta-schema');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 9 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('require-meta-schema', rule, {
   valid: [
     `
@@ -61,7 +63,7 @@ ruleTester.run('require-meta-schema', rule, {
           create(context) { const options = context.options; }
         };
       `,
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     // Variable schema with array value.
     `
@@ -254,7 +256,6 @@ schema: []
         };
       `,
       output: null,
-      parserOptions: { sourceType: 'module' },
       errors: [
         {
           messageId: 'missing',
@@ -274,6 +275,7 @@ schema: []
           ],
         },
       ],
+      languageOptions: { sourceType: 'module' },
     },
     {
       code: `
diff --git a/tests/lib/rules/require-meta-type.js b/tests/lib/rules/require-meta-type.js
index 67babf4c..ecb99ec0 100644
--- a/tests/lib/rules/require-meta-type.js
+++ b/tests/lib/rules/require-meta-type.js
@@ -10,13 +10,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/require-meta-type');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 9 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('require-meta-type', rule, {
   valid: [
     `
@@ -33,7 +35,7 @@ ruleTester.run('require-meta-type', rule, {
           create(context) {}
         };
       `,
-      parserOptions: { sourceType: 'module' },
+      languageOptions: { sourceType: 'module' },
     },
     `
       module.exports = {
@@ -115,8 +117,8 @@ ruleTester.run('require-meta-type', rule, {
           create(context) {}
         };
       `,
-      parserOptions: { sourceType: 'module' },
       errors: [{ messageId: 'missing', type: 'ObjectExpression' }],
+      languageOptions: { sourceType: 'module' },
     },
     {
       code: `
diff --git a/tests/lib/rules/test-case-property-ordering.js b/tests/lib/rules/test-case-property-ordering.js
index 996df162..cb20b85c 100644
--- a/tests/lib/rules/test-case-property-ordering.js
+++ b/tests/lib/rules/test-case-property-ordering.js
@@ -10,13 +10,15 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/test-case-property-ordering');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 // ------------------------------------------------------------------------------
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester();
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('test-case-property-ordering', rule, {
   valid: [
     `
diff --git a/tests/lib/rules/test-case-shorthand-strings.js b/tests/lib/rules/test-case-shorthand-strings.js
index c494480f..4deddade 100644
--- a/tests/lib/rules/test-case-shorthand-strings.js
+++ b/tests/lib/rules/test-case-shorthand-strings.js
@@ -10,7 +10,7 @@
 // ------------------------------------------------------------------------------
 
 const rule = require('../../../lib/rules/test-case-shorthand-strings');
-const RuleTester = require('eslint').RuleTester;
+const RuleTester = require('../eslint-rule-tester').RuleTester;
 
 /**
  * Returns the code for some valid test cases
@@ -40,7 +40,9 @@ const UNEXPECTED_SHORTHAND_ERROR = {
 // Tests
 // ------------------------------------------------------------------------------
 
-const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
+const ruleTester = new RuleTester({
+  languageOptions: { sourceType: 'commonjs' },
+});
 ruleTester.run('test-case-shorthand-strings', rule, {
   valid: [
     // default (as-needed)