refactor(build): use tsdown, add publish validation

simplifies lots of stuff. thanks VoidZero!
- bundle ESM files, rather than distribute their source
- index.js -> index.ts to easily generate ESM and CJS types from it
- remove deprecated main, module, types fields from package.json; our
required node version supports exports field
- installed tsgo and added tsconfig.json for tsdown; now we also get
type checking in IDE
- add publint and attw checks for package.json and type resolution
issues (yay! manually testing that matrix was a pain)

Author: nickjvandyke

build.js

@@ -5,30 +5,25 @@
   "author": "Nick van Dyke",
   "license": "MIT",
   "type": "module",
-  "module": "./src/index.js",
-  "main": "./dist/index.cjs",
-  "types": "./types/index.d.ts",
   "exports": {
     "import": {
-      "types": "./types/index.d.ts",
-      "default": "./src/index.js"
+      "types": "./dist/index.d.mts",
+      "default": "./dist/index.mjs"
     },
     "require": {
-      "types": "./types/index.d.cts",
+      "types": "./dist/index.d.cts",
       "default": "./dist/index.cjs"
     }
   },
   "files": [
-    "src",
-    "types",
     "dist"
   ],
   "repository": {
     "type": "git",
     "url": "https://github.com/NickvanDyke/eslint-plugin-react-you-might-not-need-an-effect.git"
   },
   "scripts": {
-    "build": "node build.js",
+    "build": "tsdown",
     "lint": "eslint",
     "test": "mocha --recursive"
   },
@@ -45,15 +40,19 @@
     "globals": "^16.2.0"
   },
   "devDependencies": {
+    "@arethetypeswrong/core": "^0.18.2",
     "@eslint/js": "^9.28.0",
-    "esbuild": "^0.25.3",
+    "@typescript/native-preview": "^7.0.0-dev.20260408.1",
+    "attw": "^1.0.0",
     "eslint": "^9.20.1",
     "eslint-plugin-eslint-plugin": "^6.4.0",
     "eslint-plugin-n": "^17.17.0",
     "lint-staged": "^16.1.0",
     "mocha": "11.1.0",
     "prettier": "^3.5.3",
-    "simple-git-hooks": "^2.13.0"
+    "publint": "^0.3.18",
+    "simple-git-hooks": "^2.13.0",
+    "tsdown": "^0.21.7"
   },
   "peerDependencies": {
     "eslint": ">=8.40.0"

package.json

@@ -8,10 +8,8 @@ import noChainStateUpdates from "./rules/no-chain-state-updates.js";
 import noDerivedState from "./rules/no-derived-state.js";
 import noPassDataToParent from "./rules/no-pass-data-to-parent.js";
 import globals from "globals";
+import type { ESLint, Linter } from "eslint";
 
-/**
- * @type {import("eslint").ESLint.Plugin}
- */
 const plugin = {
   meta: {
     name: "react-you-might-not-need-an-effect",
@@ -30,11 +28,14 @@ const plugin = {
   },
 };
 
-const rules = (severity) =>
-  Object.keys(plugin.rules).reduce((acc, ruleName) => {
-    acc[plugin.meta.name + "/" + ruleName] = severity;
-    return acc;
-  }, {});
+const rules = (severity: "error" | "warn") =>
+  Object.keys(plugin.rules).reduce(
+    (acc, ruleName) => {
+      acc[plugin.meta.name + "/" + ruleName] = severity;
+      return acc;
+    },
+    {} as Record<string, "error" | "warn">,
+  );
 
 const languageOptions = {
   globals: {
@@ -81,4 +82,12 @@ Object.assign(plugin.configs, {
   },
 });
 
-export default plugin;
+// HACK: unsure how to type this properly because we need to gradually add fields to `plugin` so it can self-reference in the config definitions.
+export default plugin as unknown as ESLint.Plugin & {
+  configs: {
+    recommended: Linter.Config;
+    strict: Linter.Config;
+    "legacy-recommended": Linter.LegacyConfig;
+    "legacy-strict": Linter.LegacyConfig;
+  };
+};

src/index.cjs

@@ -2,7 +2,7 @@ import { ESLint } from "eslint";
 import { LegacyESLint } from "eslint/use-at-your-own-risk";
 import { js } from "./rule-tester.js";
 import assert from "assert";
-import plugin from "../src/index.js";
+import plugin from "../src/index.ts";
 
 describe("config", () => {
   const codeThatDerivesState = js`

src/index.js src/index.tssrc/index.js renamed to src/index.ts

@@ -1,5 +1,5 @@
 import { ESLint } from "eslint";
-import plugin from "../src/index.js";
+import plugin from "../src/index.ts";
 import { js } from "./rule-tester.js";
 import assert from "assert";
 

test/config.test.js

@@ -1,6 +1,6 @@
 import assert from "assert";
 import { RuleTester } from "eslint";
-import plugin from "../src/index.js";
+import plugin from "../src/index.ts";
 
 // For syntax highlighting inside code under test
 export const js = String.raw;

test/real-world.test.js

@@ -0,0 +1,7 @@
+{
+  "include": ["./src/**/*"],
+  "compilerOptions": {
+    "allowJs": true,
+    "noEmit": true
+  }
+}

test/rule-tester.js

@@ -0,0 +1,22 @@
+import { defineConfig } from "tsdown";
+
+export default defineConfig({
+  entry: ["./src/index.ts"],
+  format: ["esm", "cjs"],
+  platform: "node",
+  sourcemap: true,
+  dts: {
+    enabled: true,
+    sourcemap: true,
+    tsgo: true,
+  },
+  publint: {
+    enabled: true,
+    level: "error",
+  },
+  attw: {
+    enabled: true,
+    level: "error",
+    profile: "node16", // Ignore node10 resolution errors - we require node 14+
+  },
+});