Shift To ESM Only

.changes/esm-only.md

@@ -0,0 +1,8 @@
+---
+"@simulacrum/server": minor:enhance
+"@simulacrum/foundation-simulator": minor:enhance
+"@simulacrum/auth0-simulator": minor:enhance
+"@simulacrum/github-api-simulator": minor:enhance
+---
+
+Convert package to ESM only. All LTS are able to import ESM, both from an ESM or CJS context.

package.json

@@ -33,11 +33,14 @@
     "tsc": "pnpm -r --if-present run tsc"
   },
   "devDependencies": {
+    "@arethetypeswrong/core": "^0.18.3",
     "@types/node": "^24.0.0",
     "oxfmt": "^0.43.0",
     "oxlint": "^1.58.0",
-    "tsdown": "^0.21.7",
+    "publint": "^0.3.21",
+    "tsdown": "^0.22.2",
     "typescript": "5.8.3",
+    "unplugin-unused": "^0.5.7",
     "vitest": "^3.2.4"
   },
   "engines": {

packages/auth0/bin/start.cjs → packages/auth0/bin/start.mjs

@@ -1,13 +1,13 @@
 #!/usr/bin/env node
-const auth0APIsimulator = require("../dist/index.cjs");
+import { simulation, defaultUser } from "../dist/index.mjs";
 
-const app = auth0APIsimulator.simulation();
+const app = simulation();
 app.listen(4400, () =>
   console.log(
     `Auth0 simulation server started at https://localhost:4400\n` +
       `Visit the root route to view all available routes.\n\n` +
       `Point your configuration at this simulation server and use the default user below.\n` +
-      `Email: ${auth0APIsimulator.defaultUser.email}\nPassword: ${auth0APIsimulator.defaultUser.password}\n` +
+      `Email: ${defaultUser.email}\nPassword: ${defaultUser.password}\n` +
       `\nPress Ctrl+C to stop the server`,
   ),
 );

packages/auth0/package.json

@@ -22,14 +22,12 @@
     "type": "git",
     "url": "git+https://github.com/thefrontside/simulacrum.git"
   },
-  "bin": "bin/start.cjs",
+  "bin": "bin/start.mjs",
   "files": [
     "bin/**/*",
     "dist/**/*"
   ],
   "type": "module",
-  "main": "./dist/index.cjs",
-  "module": "./dist/index.mjs",
   "types": "./dist/index.d.cts",
   "typesVersions": {
     "*": {
@@ -42,17 +40,13 @@
   "exports": {
     ".": {
       "development": "./src/index.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.cjs"
+      "default": "./dist/index.mjs"
     },
     "./package.json": "./package.json"
   },
   "publishConfig": {
     "exports": {
-      ".": {
-        "import": "./dist/index.mjs",
-        "require": "./dist/index.cjs"
-      },
+      ".": "./dist/index.mjs",
       "./package.json": "./package.json"
     }
   },

packages/auth0/src/rules/parse-rules-files.ts

@@ -1,7 +1,7 @@
 import { extensionlessFileName } from "./extensionless-file-name.ts";
 import { assert } from "assert-ts";
-import fs from "fs";
-import path from "path";
+import fs from "node:fs";
+import path from "node:path";
 
 export function parseRulesFiles(rulesPath: string): { code: string; filename: string }[] {
   let ruleFiles = fs.readdirSync(rulesPath).filter((f) => path.extname(f) === ".js");

packages/auth0/src/rules/rules-runner.ts

@@ -1,14 +1,17 @@
 import path from "path";
 import vm from "vm";
 import fs from "fs";
+import { createRequire } from "node:module";
 import { assert } from "assert-ts";
 import { parseRulesFiles } from "./parse-rules-files.ts";
 import type { Rule, RuleContext, RuleUser } from "./types.ts";
 
 export type RulesRunner = <A, I>(user: RuleUser, context: RuleContext<A, I>) => void;
 
+const require = createRequire(import.meta.url);
+
 async function runRule<A, I>(user: RuleUser, context: RuleContext<A, I>, rule: Rule) {
-  await new Promise((resolve, reject) => {
+  await new Promise<void>((resolve, reject) => {
     let sandbox = {
       process,
       Buffer,
@@ -21,7 +24,7 @@ async function runRule<A, I>(user: RuleUser, context: RuleContext<A, I>, rule: R
       setTimeout,
       console,
       require,
-      module,
+      importMeta: import.meta,
       resolve,
       reject,
       __simulator: {
@@ -37,16 +40,18 @@ async function runRule<A, I>(user: RuleUser, context: RuleContext<A, I>, rule: R
 
     console.debug(`executing rule ${path.basename(filename)}`);
 
-    let script = new vm.Script(`
-      (async function(exports) {
-        try {
-          await (${code})(__simulator.user, __simulator.context, resolve);
-        } catch (err) {
-          console.error(err);
-          reject();
-        }
-      })(module.exports)
-    `);
+    let script = new vm.Script(
+      `
+        (async function runRule() {
+          try {
+            await (${code})(__simulator.user, __simulator.context, resolve);
+          } catch (err) {
+            console.error(err);
+            reject(err);
+          }
+        })();
+      `,
+    );
 
     script.runInContext(vmContext, {
       filename,

packages/auth0/test/ci-smoke.test.ts

@@ -9,14 +9,14 @@ process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";
 const AUTH0_URL = `https://localhost:${AUTH0_PORT}`;
 
 // Ensure built distribution is present; if not, build it so the smoke test can run locally
-if (!existsSync("./dist/index.cjs")) {
+if (!existsSync("./dist/index.mjs")) {
   console.log("ci-smoke: dist not found, running `pnpm run build`...");
   execSync("pnpm run prepack", { stdio: "inherit" });
 }
 
 // Helper to start the built auth0 service with a wellness check (reused by tests)
 function startAuth0() {
-  return useService("auth0", "node ./bin/start.cjs", {
+  return useService("auth0", "node ./bin/start.mjs", {
     wellnessCheck: {
       timeout: 30000,
       *operation(_stdio) {

packages/auth0/tsdown.config.ts

@@ -3,19 +3,19 @@ import { defineConfig } from "tsdown";
 export default defineConfig({
   name: "auth0",
   entry: "./src/index.ts",
-  exports: { devExports: "development" },
-  format: ["esm", "cjs"],
-  dts: {
-    sourcemap: true,
+  deps: {
+    // if we unbundle, we want to skip this as well
+    skipNodeModulesBundle: true,
   },
+  exports: { devExports: "development" },
+  format: ["esm"],
   copy: [{ from: "src/views/public", to: "dist", flatten: false }],
   // not really required and can mangle things
   minify: false,
   // don't bundle up as have some relative path imports for static assets
   unbundle: true,
-  // if we unbundle, we want to skip this as well
-  skipNodeModulesBundle: true,
+  unused: true,
   // runs with @arethetypeswrong/core which checks types
-  attw: true,
+  attw: { profile: "esm-only" },
   publint: true,
 });

packages/foundation/package.json

@@ -25,8 +25,6 @@
     "src"
   ],
   "type": "module",
-  "main": "./dist/index.cjs",
-  "module": "./dist/index.mjs",
   "types": "./dist/index.d.cts",
   "typesVersions": {
     "*": {
@@ -39,17 +37,13 @@
   "exports": {
     ".": {
       "development": "./src/index.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.cjs"
+      "default": "./dist/index.mjs"
     },
     "./package.json": "./package.json"
   },
   "publishConfig": {
     "exports": {
-      ".": {
-        "import": "./dist/index.mjs",
-        "require": "./dist/index.cjs"
-      },
+      ".": "./dist/index.mjs",
       "./package.json": "./package.json"
     }
   },
@@ -75,8 +69,7 @@
     "express": "^5.2.1",
     "fdir": "^6.5.0",
     "http-proxy-middleware": "^3.0.5",
-    "lodash": "^4.17.23",
-    "openapi-backend": "^5.16.1",
+    "openapi-backend": "^5.17.0",
     "starfx": "0.16.0"
   },
   "devDependencies": {

packages/foundation/tsdown.config.ts

@@ -3,13 +3,17 @@ import { defineConfig } from "tsdown";
 export default defineConfig({
   name: "foundation",
   entry: "./src/index.ts",
-  exports: { devExports: "development" },
-  format: ["esm", "cjs"],
-  dts: {
-    sourcemap: true,
+  deps: {
+    // if we unbundle, we want to skip this as well
+    skipNodeModulesBundle: true,
   },
+  exports: { devExports: "development" },
+  format: ["esm"],
   minify: false,
+  // don't bundle up as have some relative path imports for static assets
+  unbundle: true,
+  unused: true,
   // runs with @arethetypeswrong/core which checks types
-  attw: true,
+  attw: { profile: "esm-only" },
   publint: true,
 });

packages/github-api/bin/start.cjs → packages/github-api/bin/start.mjs

@@ -1,7 +1,7 @@
 #!/usr/bin/env node
-const githubAPIsimulator = require("../dist/index.cjs");
+import { simulation } from "../dist/index.mjs";
 
-const app = githubAPIsimulator.simulation();
+const app = simulation();
 app.listen(3300, () =>
   console.log(`github-api simulation server started at http://localhost:3300`),
 );

packages/github-api/package.json

@@ -19,7 +19,7 @@
     "url": "git+https://github.com/thefrontside/simulacrum.git",
     "directory": "packages/github-api"
   },
-  "bin": "bin/start.cjs",
+  "bin": "bin/start.mjs",
   "files": [
     "README.md",
     "dist",
@@ -28,8 +28,6 @@
     "repository-mock-data"
   ],
   "type": "module",
-  "main": "./dist/index.cjs",
-  "module": "./dist/index.mjs",
   "types": "./dist/index.d.cts",
   "typesVersions": {
     "*": {
@@ -42,17 +40,13 @@
   "exports": {
     ".": {
       "development": "./src/index.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.cjs"
+      "default": "./dist/index.mjs"
     },
     "./package.json": "./package.json"
   },
   "publishConfig": {
     "exports": {
-      ".": {
-        "import": "./dist/index.mjs",
-        "require": "./dist/index.cjs"
-      },
+      ".": "./dist/index.mjs",
       "./package.json": "./package.json"
     }
   },

packages/github-api/tsdown.config.ts

@@ -3,15 +3,17 @@ import { defineConfig } from "tsdown";
 export default defineConfig({
   name: "github-api",
   entry: "./src/index.ts",
-  exports: { devExports: "development" },
-  format: ["esm", "cjs"],
-  dts: {
-    sourcemap: true,
+  deps: {
+    // if we unbundle, we want to skip this as well
+    skipNodeModulesBundle: true,
   },
-  // handles dirname
-  shims: true,
+  exports: { devExports: "development" },
+  format: ["esm"],
   minify: false,
+  unused: true,
+  // don't bundle up as have some relative path imports for static assets
+  unbundle: true,
   // runs with @arethetypeswrong/core which checks types
-  attw: true,
+  attw: { profile: "esm-only" },
   publint: true,
 });

packages/server/package.json

@@ -26,8 +26,6 @@
     "src"
   ],
   "type": "module",
-  "main": "./dist/index.cjs",
-  "module": "./dist/index.mjs",
   "types": "./dist/index.d.cts",
   "typesVersions": {
     "*": {
@@ -40,17 +38,13 @@
   "exports": {
     ".": {
       "development": "./src/index.ts",
-      "import": "./dist/index.mjs",
-      "require": "./dist/index.cjs"
+      "default": "./dist/index.mjs"
     },
     "./package.json": "./package.json"
   },
   "publishConfig": {
     "exports": {
-      ".": {
-        "import": "./dist/index.mjs",
-        "require": "./dist/index.cjs"
-      },
+      ".": "./dist/index.mjs",
       "./package.json": "./package.json"
     }
   },
@@ -75,8 +69,5 @@
   "devDependencies": {
     "@simulacrum/foundation-simulator": "workspace:^",
     "@types/picomatch": "^4.0.3"
-  },
-  "inlinedDependencies": {
-    "starfx": "0.16.0"
   }
 }

packages/server/tsdown.config.ts

@@ -3,13 +3,17 @@ import { defineConfig } from "tsdown";
 export default defineConfig({
   name: "server",
   entry: "./src/index.ts",
-  exports: { devExports: "development" },
-  format: ["esm", "cjs"],
-  dts: {
-    sourcemap: true,
+  deps: {
+    // if we unbundle, we want to skip this as well
+    skipNodeModulesBundle: true,
   },
+  exports: { devExports: "development" },
+  format: ["esm"],
   minify: false,
+  // don't bundle up as have some relative path imports for static assets
+  unbundle: true,
+  unused: true,
   // runs with @arethetypeswrong/core which checks types
-  attw: true,
+  attw: { profile: "esm-only" },
   publint: true,
 });