build(deps): migrate eslint 8 to 10 flat config + plugin updates

__tests__/importer.test.ts

@@ -45,7 +45,7 @@ describe("importer", () => {
 
   it("warns about incorrect resolving", async () => {
     const warning = await validateImport('@import "smh.css"', {
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any,@typescript-eslint/no-unsafe-return
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
       resolve: () => "lol" as any,
     });
     expect(warning).toMatchSnapshot("warning");

__tests__/index.test.ts

@@ -1,4 +1,3 @@
-/* eslint-disable @typescript-eslint/naming-convention */
 import fs from "fs-extra";
 import { rollup } from "rollup";
 import { RawSourceMap } from "source-map-js";
@@ -25,21 +24,21 @@ validateMany("basic", [
     title: "mode-fail",
     shouldFail: true,
     input: "simple/index.js",
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any,@typescript-eslint/no-unsafe-assignment
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
     options: { mode: "mash" as any },
   },
   {
     title: "use-fail",
     shouldFail: true,
     input: "simple/index.js",
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any,@typescript-eslint/no-unsafe-assignment
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
     options: { use: [false] as any },
   },
   {
     title: "use-type-fail",
     shouldFail: true,
     input: "simple/index.js",
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any,@typescript-eslint/no-unsafe-assignment
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
     options: { use: false as any },
   },
   {
@@ -64,14 +63,14 @@ validateMany("basic", [
     title: "plugin-fail",
     shouldFail: true,
     input: "simple/index.js",
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any,@typescript-eslint/no-unsafe-assignment
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
     options: { plugins: ["pulverizer"] as any },
   },
   {
     title: "plugin-type-fail",
     shouldFail: true,
     input: "simple/index.js",
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any,@typescript-eslint/no-unsafe-assignment
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
     options: { plugins: "pulverizer" as any },
   },
   {
@@ -744,9 +743,9 @@ test("augment-chunk-hash", async () => {
 
   const [foo1, bar, foo2] = outputFiles;
 
-  const foo1Hash = foo1.split(".")[1];
-  const foo2Hash = foo1.split(".")[1];
-  const barHash = bar.split(".")[1];
+  const foo1Hash = foo1.split(".", 2)[1];
+  const foo2Hash = foo1.split(".", 2)[1];
+  const barHash = bar.split(".", 2)[1];
 
   // Verify that [hash] part of the filenames is truthy
   expect(foo1Hash).toBeTruthy();

__tests__/setup.ts

@@ -1,3 +1,3 @@
 import { jest } from "@jest/globals";
-export {}; // fixes "isolatedModules" warning
+// fixes "isolatedModules" warning
 jest.setTimeout(30_000);

__tests__/url-resolver.test.ts

@@ -25,7 +25,7 @@ describe("url resolver", () => {
 
   it("warns about incorrect resolving", async () => {
     const warning = await validateUrl(".foo{background:url(bg.png)}", {
-      // eslint-disable-next-line @typescript-eslint/no-explicit-any,@typescript-eslint/no-unsafe-return
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
       resolve: () => "lol" as any,
     });
     expect(warning).toMatchSnapshot("warning");

__tests__/utils.test.ts

@@ -39,7 +39,7 @@ describe("less", () => {
     jest.unstable_mockModule("less", () => jest.fn());
     const loaders = new Loaders({ use: [["less", {}]], loaders: [], extensions: [""] });
     await expect(
-      // eslint-disable-next-line @typescript-eslint/no-unsafe-argument,@typescript-eslint/no-explicit-any
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
       loaders.process({ code: "" }, { id: "file.less" } as any),
     ).rejects.toThrowErrorMatchingSnapshot();
   });
@@ -50,7 +50,7 @@ describe("stylus", () => {
     jest.unstable_mockModule("stylus", () => jest.fn());
     const loaders = new Loaders({ use: [["stylus", {}]], loaders: [], extensions: [""] });
     await expect(
-      // eslint-disable-next-line @typescript-eslint/no-unsafe-argument,@typescript-eslint/no-explicit-any
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
       loaders.process({ code: "" }, { id: "file.styl" } as any),
     ).rejects.toThrowErrorMatchingSnapshot();
   });

eslint.config.mjs

@@ -0,0 +1,130 @@
+import js from "@eslint/js";
+import tseslint from "typescript-eslint";
+import importPlugin from "eslint-plugin-import-x";
+import jest from "eslint-plugin-jest";
+import unicorn from "eslint-plugin-unicorn";
+import prettier from "eslint-config-prettier/flat";
+import globals from "globals";
+
+export default tseslint.config(
+  // Global ignores (replaces .eslintignore)
+  {
+    ignores: [
+      "dist/**",
+      "tmp/**",
+      ".cache/**",
+      "coverage/**",
+      "docs/**",
+      "__tests__/fixtures/**",
+      "eslint.config.*",
+      "babel.config.js",
+      "runtime/**",
+    ],
+  },
+
+  // ESLint recommended
+  js.configs.recommended,
+
+  // TypeScript: parser + plugin rules (recommended, no type-aware rules)
+  ...tseslint.configs.recommended,
+
+  // Language options (replaces env + parserOptions)
+  {
+    languageOptions: {
+      ecmaVersion: "latest",
+      sourceType: "module",
+      globals: {
+        ...globals.node,
+      },
+    },
+  },
+
+  // Browser globals for runtime/inject-css.js
+  {
+    files: ["runtime/inject-css.js"],
+    languageOptions: {
+      globals: {
+        ...globals.browser,
+      },
+    },
+  },
+
+  // import plugin
+  importPlugin.flatConfigs.recommended,
+  {
+    settings: {
+      "import-x/resolver": {
+        node: { extensions: [".mjs", ".js", ".cjs", ".json", ".ts"] },
+      },
+    },
+  },
+
+  // unicorn recommended
+  {
+    ...unicorn.configs.recommended,
+    files: ["**/*.{js,ts,mjs,cjs}"],
+  },
+
+  // jest plugin (scoped to test files)
+  {
+    files: ["__tests__/**/*.{ts,js}"],
+    ...jest.configs["flat/recommended"],
+  },
+
+  // Custom rules
+  {
+    rules: {
+      "no-await-in-loop": "error",
+      "no-var": "error",
+      "prefer-const": "error",
+      "prefer-template": "error",
+      "sort-vars": "error",
+      // Preserve old behavior: allow unused catch arguments
+      "no-unused-vars": "off",
+      "@typescript-eslint/no-unused-vars": ["error", { caughtErrors: "none" }],
+      yoda: ["error", "never", { exceptRange: true }],
+
+      // unicorn overrides
+      // renamed: prefer-json-parse-buffer -> consistent-json-file-read, prevent-abbreviations -> name-replacements
+      "unicorn/no-null": "off",
+      "unicorn/consistent-json-file-read": "off",
+      "unicorn/prefer-module": "off",
+      "unicorn/prefer-node-protocol": "off",
+      "unicorn/prefer-set-has": "off",
+      "unicorn/name-replacements": "off",
+      // new v72 rules that are too noisy for this project
+      "unicorn/filename-case": "off",
+      "unicorn/no-anonymous-default-export": "off",
+      "unicorn/no-array-sort": "off",
+      "unicorn/no-unreadable-for-of-expression": "off",
+      "unicorn/no-this-outside-of-class": "off",
+      "unicorn/no-unsafe-string-replacement": "off",
+      "unicorn/no-break-in-nested-loop": "off",
+      "unicorn/no-return-array-push": "off",
+      "unicorn/prefer-await": "off",
+      "unicorn/max-nested-calls": "off",
+      "unicorn/import-style": "off",
+      "unicorn/require-array-sort-compare": "off",
+      "unicorn/no-computed-property-existence-check": "off",
+      "unicorn/consistent-boolean-name": "off",
+      "unicorn/no-top-level-assignment-in-function": "off",
+      "unicorn/prefer-simple-condition-first": "off",
+      "unicorn/no-declarations-before-early-exit": "off",
+      "unicorn/no-array-reverse": "off",
+      "unicorn/prefer-code-point": "off",
+
+      // import-x: can't verify named exports from .ts files without type info
+      "import-x/named": "off",
+
+      // TS: allow createRequire (used for CJS interop)
+      "@typescript-eslint/no-require-imports": "off",
+      // TS: allow empty interfaces (used for type extension pattern)
+      "@typescript-eslint/no-empty-object-type": "off",
+      // TS: allow expression statements (used in test helpers)
+      "@typescript-eslint/no-unused-expressions": "off",
+    },
+  },
+
+  // prettier must be last
+  prettier,
+);