Upgrade ESLint to v9

eslint.config.js

@@ -0,0 +1,50 @@
+import js from "@eslint/js";
+import import_ from "eslint-plugin-import";
+import node from "eslint-plugin-n";
+import promise from "eslint-plugin-promise";
+import globals from "globals";
+import ts from "typescript-eslint";
+
+export default ts.config(
+  {
+    ignores: [".makefiles", "artifacts"],
+  },
+  js.configs.recommended,
+  // eslint-disable-next-line import/no-named-as-default-member
+  ...ts.configs.recommended,
+  node.configs["flat/recommended-module"],
+  import_.flatConfigs.recommended,
+  import_.flatConfigs.typescript,
+  promise.configs["flat/recommended"],
+  {
+    languageOptions: {
+      ecmaVersion: 2022,
+      sourceType: "module",
+      globals: {
+        ...globals.es2022,
+        ...globals.node,
+      },
+    },
+    settings: {
+      "import/resolver": {
+        typescript: true,
+        node: true,
+      },
+    },
+    rules: {
+      "@typescript-eslint/no-unused-vars": [
+        "error",
+        {
+          // allow unused args if they start with _
+          argsIgnorePattern: "^_",
+        },
+      ],
+      // handled by import/no-unresolved
+      "n/no-missing-import": "off",
+      // don't check for unsupported features - too much config to make this work
+      "n/no-unsupported-features/es-builtins": "off",
+      "n/no-unsupported-features/es-syntax": "off",
+      "n/no-unsupported-features/node-builtins": "off",
+    },
+  },
+);

package.json

@@ -58,7 +58,7 @@
     "/artifacts/dist/"
   ],
   "engines": {
-    "node": ">=14"
+    "node": ">=18"
   },
   "scripts": {
     "prepublishOnly": "make artifacts/dist"
@@ -75,27 +75,29 @@
   },
   "devDependencies": {
     "@arethetypeswrong/cli": "^0.16.4",
+    "@eslint/js": "^9.14.0",
     "@skypack/package-check": "^0.2.2",
     "@stryker-mutator/core": "^8.0.0",
     "@stryker-mutator/typescript-checker": "^8.0.0",
     "@stryker-mutator/vitest-runner": "^8.2.6",
+    "@types/eslint__js": "^8.42.3",
     "@types/mdast": "^4.0.3",
     "@types/node": "^22.0.0",
-    "@typescript-eslint/eslint-plugin": "^8.0.0",
-    "@typescript-eslint/parser": "^8.0.0",
     "@vitest/coverage-v8": "^2.0.0",
-    "eslint": "^8.17.0",
-    "eslint-config-prettier": "^9.0.0",
-    "eslint-import-resolver-typescript": "^3.2.5",
-    "eslint-plugin-import": "^2.26.0",
-    "eslint-plugin-n": "^17.0.0",
-    "eslint-plugin-promise": "^7.0.0",
-    "eslint-plugin-vitest": "^0.4.0",
+    "@vitest/eslint-plugin": "^1.1.7",
+    "eslint": "^9.14.0",
+    "eslint-config-prettier": "^9.1.0",
+    "eslint-import-resolver-typescript": "^3.6.3",
+    "eslint-plugin-import": "^2.31.0",
+    "eslint-plugin-n": "^17.12.0",
+    "eslint-plugin-promise": "^7.1.0",
+    "globals": "^15.12.0",
     "prettier": "^3.0.0",
     "prettier-plugin-organize-imports": "^4.0.0",
     "publint": "^0.2.12",
     "ts-node": "^10.9.1",
     "typescript": "^5.0.4",
+    "typescript-eslint": "^8.13.0",
     "vite-tsconfig-paths": "^5.1.0",
     "vitest": "^2.0.0"
   }

test/suite/specification-prettier.spec.ts

@@ -38,7 +38,6 @@ describe("Specification documents (Prettier unavailable)", () => {
 
   describe("when Prettier is not installed", () => {
     beforeAll(() => {
-      // eslint-disable-next-line @typescript-eslint/require-await
       vi.doMock("prettier", async () => {
         throw new Error('Cannot find module "prettier"');
       });
@@ -63,14 +62,12 @@ describe("Specification documents (Prettier unavailable)", () => {
 
   describe("when Prettier is installed but not configured", () => {
     beforeAll(() => {
-      // eslint-disable-next-line @typescript-eslint/require-await
       vi.doMock("prettier", async () => {
         const prettier = await vi.importActual("prettier");
 
         return {
           ...prettier,
 
-          // eslint-disable-next-line @typescript-eslint/require-await
           async resolveConfig() {
             return null;
           },