add support for eslint-9

.github/workflows/tests.yaml

@@ -35,10 +35,18 @@ jobs:
         eslint-version:
           - 7
           - 8
+          - 9
         node-version:
           - 14
           - 16
           - 18
+          - 20
+      exclude:
+        # eslint@9 requires node 18+
+        - eslint-version: 9
+          node-version: 14
+        - eslint-version: 9
+          node-version: 16
 
     steps:
     - uses: actions/checkout@v4

lib/ignore-all.js

@@ -52,11 +52,16 @@ module.exports = async function ignoreAll(cwd = process.cwd()) {
 
   const eslint = importCwd('eslint');
 
-  if (semver.intersects(eslintVersion, '8')) {
+  if (
+    semver.intersects(eslintVersion, '8') ||
+    semver.intersects(eslintVersion, '9')
+  ) {
     // this won't use the version in the repo but it will still use v8 because
     // that is installed in this repo
     const { ESLint } = eslint;
-    cli = new ESLint();
+    cli = new ESLint({
+      cwd,
+    });
     results = await cli.lintFiles([cwd]);
 
     // remove warnings

package.json

@@ -16,6 +16,7 @@
   "devDependencies": {
     "@babel/core": "^7.25.2",
     "@babel/eslint-parser": "^7.19.1",
+    "@eslint/js": "^9.13.0",
     "chai": "^4.3.4",
     "eslint": "^8.0.0",
     "eslint-config-prettier": "^9.1.0",

test/ignore.mjs

@@ -9,6 +9,12 @@ async function ignoreTestFile(input, files) {
   const project = new Project({
     files: {
       '.eslintrc.json': '{"extends": "eslint:recommended"}',
+      //only for eslint 9
+      'eslint.config.js': `const js = require("@eslint/js");
+
+module.exports = [
+    js.configs.recommended,
+];`,
       'index.js': input,
       'package.json': `{
         "devDependencies": {
@@ -20,6 +26,7 @@ async function ignoreTestFile(input, files) {
   });
 
   project.linkDevDependency('eslint', { baseDir: process.cwd() });
+  project.linkDevDependency('@eslint/js', { baseDir: process.cwd() });
   await project.write();
   await ignoreAll(project.baseDir);
 
@@ -82,6 +89,13 @@ if (10 === 'false') {
         {
           '.eslintrc.json':
             '{"extends": "eslint:recommended", "rules": { "no-constant-condition": "warn" }}',
+          //only for eslint 9
+          'eslint.config.js': `const js = require("@eslint/js");
+
+          module.exports = [
+              js.configs.recommended,
+              { rules: { "no-constant-condition": "warn" }}
+          ];`,
         },
       ),
     ).to.equal(`/* eslint-disable no-debugger */