Update ESLint to v10.2.0, sort type members

.dockerignore

@@ -2,7 +2,7 @@
 !.clang-format
 !.editorconfig
 !entry.ts
-!eslint.config.js
+!eslint.config.mjs
 !ruff.toml
 !stylesheet.xml
 !svgo.config.js

Dockerfile

@@ -59,24 +59,14 @@ echo 'source /black21-venv/bin/activate && black "$@"' > /usr/bin/black21
 chmod +x /usr/bin/black21
 
 # Install Node dependencies
-#
-# We stay on eslint-plugin-unicorn 56.0.1 because 57+ removed support for
-# importing this plugin into the ESLint config as CommonJS. (We use CommonJS
-# instead of ESM in the ESLint config mainly because the latter requires a new
-# local package.json file that declares `"type": "module"`, which interferes
-# with other tools like SVGO). I couldn't get the `deasync` hack to work - it
-# just hung forever. TODO: Try updating this plugin after updating Node.js to
-# v22+, which has experimental support for synchronously require()-ing ESM?
-# https://github.com/sindresorhus/eslint-plugin-unicorn/releases/tag/v57.0.0
-# https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
-# https://nodejs.org/en/blog/announcements/v22-release-announce#support-requireing-synchronous-esm-graphs
-# https://github.com/eslint/eslint/issues/13684#issuecomment-722949152
 npm install -g \
+  @eslint/compat@2.0.5 \
   @prettier/plugin-xml@3.4.2 \
-  eslint@9.39.2 \
+  eslint@10.2.0 \
   eslint-plugin-jsdoc@62.9.0 \
+  eslint-plugin-perfectionist@5.8.0 \
   eslint-plugin-sort-keys@2.3.5 \
-  eslint-plugin-unicorn@56.0.1 \
+  eslint-plugin-unicorn@64.0.0 \
   prettier@3.8.3 \
   svgo@4.0.1 \
   typescript-eslint@8.58.2
@@ -133,3 +123,5 @@ COPY --from=entry /entry.js /entry
 ENV COURSIER_CACHE=/tmp/coursier-cache
 ENV COURSIER_JVM_CACHE=/tmp/coursier-jvm-cache
 ENV NODE_PATH=/usr/local/lib/node_modules
+# .mjs import resolution doesn't respect NODE_PATH
+RUN ln -s /usr/local/lib/node_modules /node_modules

README.md

@@ -7,7 +7,7 @@ This repo contains [pre-commit](https://pre-commit.com/) hooks for Duolingo deve
 The main hook that runs several code formatters in parallel:
 
 - [Prettier](https://github.com/prettier/prettier) v3.8.3 for CSS, HTML, JS, JSX, Markdown, Sass, TypeScript, XML, YAML
-- [ESLint](https://eslint.org/) v9.39.2 for JS, TypeScript
+- [ESLint](https://eslint.org/) v10.2.0 for JS, TypeScript
 - [Ruff](https://docs.astral.sh/ruff/) v0.15.10 for Python 3
 - [Black](https://github.com/psf/black) v21.12b0 for Python 2
 - [autoflake](https://github.com/myint/autoflake) v1.7.8 for Python <!-- TODO: Upgrade to v2+, restrict to Python 2, and reenable Ruff rule F401 once our Python 3 repos that were converted from Python 2 no longer use type hint comments: https://github.com/PyCQA/autoflake/issues/222#issuecomment-1419089254 -->

entry.ts

@@ -183,7 +183,7 @@ const HOOKS: Record<HookName, Hook> = {
           "eslint",
           "--fix",
           "--config",
-          "/eslint.config.js",
+          "/eslint.config.mjs",
           ...sources,
         );
       } catch {

eslint.config.js → eslint.config.mjs

@@ -1,8 +1,11 @@
-const { defineConfig } = require("eslint/config");
-const jsdoc = require("eslint-plugin-jsdoc");
-const sortKeys = require("eslint-plugin-sort-keys");
-const unicorn = require("eslint-plugin-unicorn");
-const tseslint = require("typescript-eslint");
+import { fixupPluginRules } from "@eslint/compat";
+import { defineConfig } from "eslint/config";
+import perfectionist from "eslint-plugin-perfectionist";
+import { Alphabet } from "eslint-plugin-perfectionist/alphabet";
+import jsdoc from "eslint-plugin-jsdoc";
+import sortKeys from "eslint-plugin-sort-keys";
+import unicorn from "eslint-plugin-unicorn";
+import tseslint from "typescript-eslint";
 
 const config = {
   files: ["**/*.{js,jsx,mjs,ts,tsx}"],
@@ -19,7 +22,8 @@ const config = {
   plugins: {
     "@typescript-eslint": tseslint.plugin,
     jsdoc,
-    "sort-keys": sortKeys,
+    perfectionist,
+    "sort-keys": fixupPluginRules(sortKeys),
     unicorn,
   },
   //
@@ -90,7 +94,7 @@ const config = {
     // repo-agnostic way. One compromise might be to use `import/order` and
     // simply disable its regrouping feature in favor of whatever groups are
     // found in the source code to be formatted, but no such option exists :/
-    "sort-imports": ["error", { ignoreDeclarationSort: true }],
+    // "sort-imports": ["error", { ignoreDeclarationSort: true }], // Replaced by perfectionist/sort-named-imports
     "sort-vars": "error",
     // "strict": "error",
     // "unicode-bom": "error",
@@ -132,6 +136,19 @@ const config = {
     // "jsdoc/tag-lines": "error",
     // "jsdoc/text-escaping": "error",
 
+    // perfectionist rules. https://perfectionist.dev/rules
+    // "perfectionist/sort-enums" // Reordering can change numeric enum values
+    // "perfectionist/sort-heritage-clauses" // Not worth the churn when interfaces are involved
+    // "perfectionist/sort-imports" // TODO: Enable once grouping is more configurable
+    "perfectionist/sort-interfaces": "error",
+    // "perfectionist/sort-intersection-types" // Not worth the churn when interfaces are involved
+    "perfectionist/sort-named-exports": "error",
+    "perfectionist/sort-named-imports": "error",
+    "perfectionist/sort-object-types": "error",
+    // "perfectionist/sort-objects // Prefer sort-keys because it leaves computed properties alone
+    // "perfectionist/sort-switch-case" // TODO: Enable once it supports partitionByNewLine
+    // "perfectionist/sort-union-types" // Not worth the churn when interfaces are involved
+
     // sort-keys rules. https://github.com/namnm/eslint-plugin-sort-keys
     "sort-keys/sort-keys-fix": ["error", "asc", { natural: true }],
 
@@ -155,13 +172,7 @@ const config = {
     ],
     // "@typescript-eslint/consistent-type-definitions": ["error", "interface"], // Can cause `Index signature for type 'string' is missing in type`
     // "@typescript-eslint/consistent-type-imports": ["error", { disallowTypeAnnotations: false, prefer: "type-imports" }], // TODO: Enable once all our code is on TS 3.8+
-    "@typescript-eslint/explicit-member-accessibility": [
-      "error",
-      {
-        accessibility: "explicit",
-        overrides: { accessors: "explicit", constructors: "explicit" },
-      },
-    ],
+    // "@typescript-eslint/explicit-member-accessibility" // Buggy? Doesn't actually add `public` when absent
     // "@typescript-eslint/method-signature-style": "error",
     "@typescript-eslint/no-array-constructor": "error",
     // "@typescript-eslint/no-dynamic-delete": "error",
@@ -182,17 +193,17 @@ const config = {
     "unicorn/consistent-destructuring": "error",
     "unicorn/consistent-empty-array-spread": "error",
     // "unicorn/consistent-existence-index-check": "error",
+    // "unicorn/consistent-template-literal-escape": "error",
     // "unicorn/custom-error-definition": "error",
     // "unicorn/empty-brace-spaces": "error",
     // "unicorn/escape-case": "error", // Implemented by Prettier
     // "unicorn/explicit-length-check": "error",
     // "unicorn/new-for-builtins": "error",
     // "unicorn/no-array-for-each": "error", // Bug: fixer deletes comments
     // "unicorn/no-array-method-this-argument": "error",
-    // "unicorn/no-array-push-push": "error", // Bug: fixer deletes comments
     // "unicorn/no-await-expression-member": "error",
     "unicorn/no-console-spaces": "error",
-    // "unicorn/no-for-loop": "error", // Bug: https://github.com/sindresorhus/eslint-plugin-unicorn/issues/1802
+    "unicorn/no-for-loop": "error",
     // "unicorn/no-hex-escape": "error",
     // "unicorn/no-lonely-if": "error", // Bug: Moves comments around
     "unicorn/no-negated-condition": "error",
@@ -207,12 +218,13 @@ const config = {
     "unicorn/no-unnecessary-await": "error",
     "unicorn/no-unreadable-array-destructuring": "error",
     "unicorn/no-useless-fallback-in-spread": "error",
+    // "unicorn/no-useless-iterator-to-array": "error",
     // "unicorn/no-useless-length-check": "error",
     // "unicorn/no-useless-promise-resolve-reject": "error", // Conflicts with @typescript-eslint/no-throw-literal
     "unicorn/no-useless-spread": "error",
     // "unicorn/no-useless-undefined": "error", // Doesn't play well with TS
     "unicorn/no-zero-fractions": "error",
-    "unicorn/number-literal-case": "error",
+    // "unicorn/number-literal-case": "error", // Implemented by Prettier
     // "unicorn/numeric-separators-style": "error",
     // "unicorn/prefer-add-event-listener": "error",
     // "unicorn/prefer-array-find": "error", // Doesn't play well with TS, which types `filter(...)[0]` as non-undefined
@@ -249,6 +261,8 @@ const config = {
     "unicorn/prefer-regexp-test": "error",
     // "unicorn/prefer-set-has": "error",
     "unicorn/prefer-set-size": "error",
+    // "unicorn/prefer-simple-condition-first": "error",
+    // "unicorn/prefer-single-call": "error", // Bug: fixer deletes comments
     // "unicorn/prefer-spread": "error", // Bug: https://github.com/sindresorhus/eslint-plugin-unicorn/issues/2041
     // "unicorn/prefer-string-raw": "error",
     // "unicorn/prefer-string-replace-all": "error",
@@ -264,12 +278,29 @@ const config = {
     // "unicorn/require-number-to-fixed-digits-argument": "error",
     // "unicorn/string-content": "error",
     // "unicorn/switch-case-braces": "error",
+    // "unicorn/switch-case-break-position": "error",
     // "unicorn/template-indent": "error",
     "unicorn/text-encoding-identifier-case": "error",
     // "unicorn/throw-new-error": "error",
 
     /* eslint-enable */
   },
+  settings: {
+    perfectionist: {
+      // By default, perfectionist sorts lowercase before uppercase. We reverse
+      // that behavior here to match our existing pre-2026 convention, which is
+      // also arguably more sensible from a coding perspective because it
+      // prioritizes SCREAMING_SNAKE_CASE constants, similar to how such
+      // constants are typically defined first in a source file
+      alphabet: Alphabet.generateRecommendedAlphabet()
+        .placeAllWithCaseBeforeAllWithOtherCase("uppercase")
+        .getCharacters(),
+      ignoreCase: false,
+      order: "asc",
+      partitionByNewLine: true,
+      type: "custom",
+    },
+  },
 };
 
-module.exports = defineConfig([config]);
+export default defineConfig([config]);

test/after/hello.ts

@@ -21,3 +21,27 @@ try {
     console.log("hi", `world${ex}`);
   }
 }
+
+interface Serializable {
+  serialize(): string;
+}
+interface Printable {
+  print(): void;
+}
+class Report implements Serializable, Printable {
+  print(): void {}
+  serialize(): string {
+    return "";
+  }
+}
+
+interface Options {
+  Cache: boolean;
+  Format: string;
+  debug: boolean;
+  verbose: boolean;
+}
+
+type Point = { x: number; y: number };
+
+export type { Combined, Level, Options, Point };

test/before/hello.ts

@@ -1,4 +1,3 @@
-
 import   {  execSync , execFile }  from  "child_process"  ;
  import  {  writeFile,  FSWatcher, readFile  }  from  "fs" ;
 
@@ -25,3 +24,21 @@ try  {
   }catch( err)  {
 if  (8.00  > foo!!) console.log("hi ", "world" + err);
 }
+
+interface Serializable { serialize(): string }
+interface Printable { print(): void }
+class Report implements Serializable, Printable {
+  print(): void {}
+  serialize(): string { return "" }
+}
+
+interface Options {
+  verbose: boolean;
+  Format: string;
+  debug: boolean;
+  Cache: boolean;
+}
+
+type Point = { y: number; x: number };
+
+export type { Options, Combined, Level, Point };