From 365e0b776db93c4e883bce6e0225449a9bdebd14 Mon Sep 17 00:00:00 2001
From: Kyle Herock <kherock@gmail.com>
Date: Sun, 27 Mar 2022 20:10:24 -0400
Subject: [PATCH 1/2] Replace resolve with require.resolve

---
 lib/cfg.js          |  5 +----
 lib/index.js        |  9 +++------
 lib/local-path.js   |  2 --
 lib/notify.js       |  4 +---
 lib/resolve-main.js |  7 -------
 lib/wrap.js         | 12 ++++--------
 package.json        |  3 +--
 7 files changed, 10 insertions(+), 32 deletions(-)
 delete mode 100644 lib/local-path.js
 delete mode 100644 lib/resolve-main.js

diff --git a/lib/cfg.js b/lib/cfg.js
index bf0e795..37f698a 100644
--- a/lib/cfg.js
+++ b/lib/cfg.js
@@ -1,8 +1,6 @@
 const { existsSync, readFileSync } = require('fs');
 const { dirname, resolve } = require('path');
 
-const resolveMain = require('./resolve-main');
-
 const defaultConfig = {
   clear: false,
   debounce: 10,
@@ -30,8 +28,7 @@ function read(dir) {
 }
 
 function getConfig(script) {
-  const main = resolveMain(script);
-  const dir = main ? dirname(main) : '.';
+  const dir = resolve(dirname(script));
 
   return Object.assign(
     defaultConfig,
diff --git a/lib/index.js b/lib/index.js
index b4ecea6..f087999 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -1,16 +1,13 @@
 const { fork } = require('child_process');
 const filewatcher = require('filewatcher');
-const { join } = require('path');
 const semver = require('semver');
 const { pathToFileURL } = require('url');
 
 const { clearFactory } = require('./clear');
 const { configureDeps, configureIgnore } = require('./ignore');
 const ipc = require('./ipc');
-const localPath = require('./local-path');
 const logFactory = require('./log');
 const notifyFactory = require('./notify');
-const resolveMain = require('./resolve-main');
 
 module.exports = function (
   script,
@@ -56,7 +53,7 @@ module.exports = function (
   const isTooDeep = configureDeps(deps);
 
   // Run ./dedupe.js as preload script
-  if (dedupe) process.env.NODE_DEV_PRELOAD = localPath('dedupe');
+  if (dedupe) process.env.NODE_DEV_PRELOAD = require.resolve('./dedupe');
 
   const watcher = filewatcher({ debounce, forcePolling, interval });
   let isPaused = false;
@@ -94,11 +91,11 @@ module.exports = function (
 
     const args = nodeArgs.slice();
 
-    args.push(`--require=${resolveMain(localPath('wrap'))}`);
+    args.push(`--require=${require.resolve('./wrap')}`);
 
     const loaderName = semver.satisfies(process.version, '>=16.12.0') ? 'load' : 'get-format';
 
-    const loaderURL = pathToFileURL(resolveMain(localPath(join('loaders', `${loaderName}.mjs`))));
+    const loaderURL = pathToFileURL(require.resolve(`./loaders/${loaderName}.mjs`));
 
     args.push(`--experimental-loader=${loaderURL.href}`);
 
diff --git a/lib/local-path.js b/lib/local-path.js
deleted file mode 100644
index 57a6131..0000000
--- a/lib/local-path.js
+++ /dev/null
@@ -1,2 +0,0 @@
-const { join } = require('path');
-module.exports = f => join(__dirname, f);
diff --git a/lib/notify.js b/lib/notify.js
index 2daaa3b..aadd579 100644
--- a/lib/notify.js
+++ b/lib/notify.js
@@ -1,8 +1,6 @@
 const notifier = require('node-notifier');
 
-const localPath = require('./local-path');
-
-const iconLevelPath = level => localPath(`../icons/node_${level}.png`);
+const iconLevelPath = level => require.resolve(`../icons/node_${level}.png`);
 
 // Writes a message to the console and optionally displays a desktop notification.
 module.exports = (notifyEnabled, log) => {
diff --git a/lib/resolve-main.js b/lib/resolve-main.js
deleted file mode 100644
index a54c12a..0000000
--- a/lib/resolve-main.js
+++ /dev/null
@@ -1,7 +0,0 @@
-const { sync: resolve } = require('resolve');
-
-module.exports = main => {
-  const basedir = process.cwd();
-  const paths = [basedir];
-  return resolve(main, { basedir, paths });
-};
diff --git a/lib/wrap.js b/lib/wrap.js
index 7889ea5..71d1a63 100755
--- a/lib/wrap.js
+++ b/lib/wrap.js
@@ -1,12 +1,10 @@
 const { dirname, extname } = require('path');
 const childProcess = require('child_process');
-const { sync: resolve } = require('resolve');
 const { isMainThread } = require('worker_threads');
 
 const { getConfig } = require('./cfg');
 const hook = require('./hook');
 const { relay, send } = require('./ipc');
-const resolveMain = require('./resolve-main');
 const suppressExperimentalWarnings = require('./suppress-experimental-warnings');
 
 // Experimental warnings need to be suppressed in worker threads as well, since
@@ -18,7 +16,7 @@ suppressExperimentalWarnings(process);
 // on the main thread.
 if (!isMainThread) return;
 
-const script = process.argv[1];
+const script = require.resolve(process.argv[1]);
 const { extensions, fork, vm } = getConfig(script);
 
 if (process.env.NODE_DEV_PRELOAD) {
@@ -58,18 +56,16 @@ process.on('uncaughtException', err => {
 hook(vm, required => send({ required }));
 
 // Check if a module is registered for this extension
-const main = resolveMain(script);
-const ext = extname(main).slice(1);
+const ext = extname(script).slice(1);
 const mod = extensions[ext];
-const basedir = dirname(main);
 
 // Support extensions where 'require' returns a function that accepts options
 if (typeof mod === 'object' && mod.name) {
-  const fn = require(resolve(mod.name, { basedir }));
+  const fn = require(require.resolve(mod.name, { paths: [dirname(script)] }));
   if (typeof fn === 'function' && mod.options) {
     // require returned a function, call it with options
     fn(mod.options);
   }
 } else if (typeof mod === 'string') {
-  require(resolve(mod, { basedir }));
+  require(require.resolve(mod, { paths: [dirname(script)] }));
 }
diff --git a/package.json b/package.json
index 96afe80..15cdda9 100644
--- a/package.json
+++ b/package.json
@@ -38,7 +38,6 @@
     "get-package-type": "^0.1.0",
     "minimist": "^1.2.6",
     "node-notifier": "^8.0.1",
-    "resolve": "^1.22.0",
     "semver": "^7.3.7"
   },
   "devDependencies": {
@@ -58,4 +57,4 @@
     "*.{js,mjs}": "eslint --cache --fix",
     "*.{js,md}": "prettier --write"
   }
-}
+}
\ No newline at end of file

From 0f7a7f7de7e7ddea8e9d11ecc183aabed89d244e Mon Sep 17 00:00:00 2001
From: Kyle Herock <kherock@gmail.com>
Date: Sun, 27 Mar 2022 20:43:35 -0400
Subject: [PATCH 2/2] Port to ESM

---
 .eslintrc                                     | 13 +---
 README.md                                     |  1 +
 bin/node-dev                                  | 13 ----
 bin/node-dev.js                               |  8 ++
 lib/{cfg.js => cfg.cjs}                       |  3 +-
 lib/clear.js                                  |  6 +-
 lib/cli.js                                    | 10 +--
 lib/hook.js                                   | 60 ---------------
 lib/ignore.js                                 |  6 +-
 lib/index.js                                  | 52 +++++++------
 lib/ipc.cjs                                   | 52 +++++++++++++
 lib/ipc.js                                    | 43 ++++++++++-
 lib/loaders/get-format.mjs                    |  2 +-
 lib/loaders/ipc.mjs                           |  5 --
 lib/loaders/load.mjs                          |  2 +-
 lib/{log.js => log.cjs}                       |  0
 lib/notify.js                                 |  8 +-
 lib/{ => require}/dedupe.js                   |  0
 lib/require/package.json                      |  3 +
 lib/require/patch-fork.js                     | 11 +++
 lib/require/patch-vm.js                       | 25 ++++++
 lib/require/patch-worker.js                   | 14 ++++
 lib/require/patch.js                          | 77 +++++++++++++++++++
 lib/require/suppress-experimental-warnings.js | 23 ++++++
 lib/suppress-experimental-warnings.js         | 25 ------
 lib/wrap.js                                   | 71 -----------------
 package.json                                  | 17 +++-
 test/cli.js                                   |  4 +-
 test/fixture/package.json                     |  3 +
 test/index.js                                 |  8 +-
 test/log.js                                   |  6 +-
 test/run.js                                   |  4 +-
 test/spawn/argv.js                            |  4 +-
 test/spawn/caught.js                          |  4 +-
 test/spawn/clear.js                           |  6 +-
 test/spawn/cli-require.js                     |  4 +-
 test/spawn/cluster.js                         |  4 +-
 test/spawn/conceal.js                         |  4 +-
 test/spawn/errors.js                          |  4 +-
 test/spawn/esmodule.js                        |  4 +-
 test/spawn/exit-code.js                       |  4 +-
 test/spawn/experimental-warnings.js           |  4 +-
 test/spawn/expose-gc.js                       |  4 +-
 test/spawn/extension-options.js               |  4 +-
 test/spawn/graceful-ipc.js                    |  4 +-
 test/spawn/index.js                           | 48 ++++++------
 test/spawn/inspect.js                         |  4 +-
 test/spawn/kill-fork.js                       |  4 +-
 test/spawn/no-such-module.js                  |  4 +-
 test/spawn/node-env.js                        |  4 +-
 test/spawn/relay-stdin.js                     |  4 +-
 test/spawn/require-extensions.js              |  4 +-
 test/spawn/restart-twice.js                   |  4 +-
 test/spawn/sigterm.js                         |  4 +-
 test/spawn/timestamps.js                      |  4 +-
 test/spawn/typescript.js                      |  4 +-
 test/spawn/uncaught.js                        |  4 +-
 test/utils.js                                 | 27 ++++---
 58 files changed, 419 insertions(+), 329 deletions(-)
 delete mode 100755 bin/node-dev
 create mode 100755 bin/node-dev.js
 rename lib/{cfg.js => cfg.cjs} (96%)
 delete mode 100644 lib/hook.js
 create mode 100644 lib/ipc.cjs
 delete mode 100644 lib/loaders/ipc.mjs
 rename lib/{log.js => log.cjs} (100%)
 rename lib/{ => require}/dedupe.js (100%)
 create mode 100644 lib/require/package.json
 create mode 100644 lib/require/patch-fork.js
 create mode 100644 lib/require/patch-vm.js
 create mode 100644 lib/require/patch-worker.js
 create mode 100644 lib/require/patch.js
 create mode 100644 lib/require/suppress-experimental-warnings.js
 delete mode 100644 lib/suppress-experimental-warnings.js
 delete mode 100755 lib/wrap.js
 create mode 100644 test/fixture/package.json

diff --git a/.eslintrc b/.eslintrc
index 230d696..77d0cd8 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -6,20 +6,13 @@
   "extends": ["eslint:recommended", "plugin:import/errors", "plugin:import/warnings"],
   "plugins": ["import"],
   "parserOptions": {
-    "ecmaVersion": 11
+    "ecmaVersion": 13,
+    "sourceType": "module"
   },
   "rules": {
     "eqeqeq": "error",
     "no-trailing-spaces": "error",
     "prefer-arrow-callback": "error",
     "semi": "error"
-  },
-  "overrides": [
-    {
-      "files": ["./**/*.mjs"],
-      "parserOptions": {
-        "sourceType": "module"
-      }
-    }
-  ]
+  }
 }
diff --git a/README.md b/README.md
index f47cde8..dc9fdf5 100644
--- a/README.md
+++ b/README.md
@@ -48,6 +48,7 @@ There are a couple of command-line options that can be used to control which fil
 - `--respawn` - Keep watching for changes after the script has exited
 - `--timestamp` - The timestamp format to use for logging restarts
 - `--vm` - Load files using Node's VM
+- `--worker` - Hook into worker_threads.Worker constructor
 
 ## Passing arguments to node
 
diff --git a/bin/node-dev b/bin/node-dev
deleted file mode 100755
index a239f82..0000000
--- a/bin/node-dev
+++ /dev/null
@@ -1,13 +0,0 @@
-#!/usr/bin/env node
-
-const dev = require('../lib');
-const cli = require('../lib/cli');
-
-const {
-  script,
-  scriptArgs,
-  nodeArgs,
-  opts
-} = cli(process.argv);
-
-dev(script, scriptArgs, nodeArgs, opts);
diff --git a/bin/node-dev.js b/bin/node-dev.js
new file mode 100755
index 0000000..ac6b462
--- /dev/null
+++ b/bin/node-dev.js
@@ -0,0 +1,8 @@
+#!/usr/bin/env node
+
+import dev from '../lib/index.js';
+import cli from '../lib/cli.js';
+
+const { script, scriptArgs, nodeArgs, opts } = cli(process.argv);
+
+dev(script, scriptArgs, nodeArgs, opts);
diff --git a/lib/cfg.js b/lib/cfg.cjs
similarity index 96%
rename from lib/cfg.js
rename to lib/cfg.cjs
index 37f698a..4d52327 100644
--- a/lib/cfg.js
+++ b/lib/cfg.cjs
@@ -19,7 +19,8 @@ const defaultConfig = {
   poll: false,
   respawn: false,
   timestamp: 'HH:MM:ss',
-  vm: true
+  vm: true,
+  worker: true
 };
 
 function read(dir) {
diff --git a/lib/clear.js b/lib/clear.js
index 9b80825..304a991 100644
--- a/lib/clear.js
+++ b/lib/clear.js
@@ -1,4 +1,2 @@
-const control = '\u001bc';
-const clearFactory = clear => (clear ? () => process.stdout.write(control) : () => {});
-
-module.exports = { clearFactory, control };
+export const control = '\u001bc';
+export const clearFactory = clear => (clear ? () => process.stdout.write(control) : () => {});
diff --git a/lib/cli.js b/lib/cli.js
index 4edc038..5e30d16 100644
--- a/lib/cli.js
+++ b/lib/cli.js
@@ -1,8 +1,8 @@
-const assert = require('assert');
-const minimist = require('minimist');
-const { resolve } = require('path');
+import assert from 'assert';
+import minimist from 'minimist';
+import { resolve } from 'path';
 
-const { getConfig } = require('./cfg');
+import { getConfig } from './cfg.cjs';
 
 const arrayify = v => (Array.isArray(v) ? [...v] : [v]);
 const argify = key => ({ arg: `--${key}`, key });
@@ -55,7 +55,7 @@ const unknownFactory = args => arg => {
   key && !nodeDevNumber.includes(key) && args.push({ arg, key });
 };
 
-module.exports = argv => {
+export default argv => {
   const nodeCustomArgs = [];
   const args = argv.slice(2).filter(nodeCustomFactory(nodeCustomArgs));
 
diff --git a/lib/hook.js b/lib/hook.js
deleted file mode 100644
index a7059dc..0000000
--- a/lib/hook.js
+++ /dev/null
@@ -1,60 +0,0 @@
-const vm = require('vm');
-
-module.exports = (patchVM, callback) => {
-  // Hook into Node's `require(...)`
-  updateHooks();
-
-  // Patch the vm module to watch files executed via one of these methods:
-  if (patchVM) {
-    patch(vm, 'createScript', 1);
-    patch(vm, 'runInThisContext', 1);
-    patch(vm, 'runInNewContext', 2);
-    patch(vm, 'runInContext', 2);
-  }
-
-  /**
-   * Patch the specified method to watch the file at the given argument
-   * index.
-   */
-  function patch(obj, method, optionsArgIndex) {
-    const orig = obj[method];
-    if (!orig) return;
-    obj[method] = function () {
-      const opts = arguments[optionsArgIndex];
-      let file = null;
-      if (opts) {
-        file = typeof opts === 'string' ? opts : opts.filename;
-      }
-      if (file) callback(file);
-      return orig.apply(this, arguments);
-    };
-  }
-
-  /**
-   * (Re-)install hooks for all registered file extensions.
-   */
-  function updateHooks() {
-    Object.keys(require.extensions).forEach(ext => {
-      const fn = require.extensions[ext];
-      if (typeof fn === 'function' && fn.name !== 'nodeDevHook') {
-        require.extensions[ext] = createHook(fn);
-      }
-    });
-  }
-
-  /**
-   * Returns a function that can be put into `require.extensions` in order to
-   * invoke the callback when a module is required for the first time.
-   */
-  function createHook(handler) {
-    return function nodeDevHook(module, filename) {
-      if (!module.loaded) callback(module.filename);
-
-      // Invoke the original handler
-      handler(module, filename);
-
-      // Make sure the module did not hijack the handler
-      updateHooks();
-    };
-  }
-};
diff --git a/lib/ignore.js b/lib/ignore.js
index a3e3078..db27d30 100644
--- a/lib/ignore.js
+++ b/lib/ignore.js
@@ -18,7 +18,5 @@ const getPrefix = mod => {
 
 const isPrefixOf = value => prefix => value.startsWith(prefix);
 
-const configureDeps = deps => required => deps !== -1 && getLevel(required) > deps;
-const configureIgnore = ignore => required => ignore.some(isPrefixOf(required));
-
-module.exports = { configureDeps, configureIgnore };
+export const configureDeps = deps => required => deps !== -1 && getLevel(required) > deps;
+export const configureIgnore = ignore => required => ignore.some(isPrefixOf(required));
diff --git a/lib/index.js b/lib/index.js
index f087999..d0a9720 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -1,15 +1,18 @@
-const { fork } = require('child_process');
-const filewatcher = require('filewatcher');
-const semver = require('semver');
-const { pathToFileURL } = require('url');
-
-const { clearFactory } = require('./clear');
-const { configureDeps, configureIgnore } = require('./ignore');
-const ipc = require('./ipc');
-const logFactory = require('./log');
-const notifyFactory = require('./notify');
-
-module.exports = function (
+import { fork } from 'child_process';
+import filewatcher from 'filewatcher';
+import { createRequire } from 'module';
+import semver from 'semver';
+
+import { clearFactory } from './clear.js';
+import { configureDeps, configureIgnore } from './ignore.js';
+import ipc from './ipc.cjs';
+import logFactory from './log.cjs';
+import notifyFactory from './notify.js';
+
+const require = createRequire(import.meta.url);
+const resolveHook = hook => require.resolve('./require/' + hook);
+
+export default function (
   script,
   scriptArgs,
   nodeArgs,
@@ -18,13 +21,16 @@ module.exports = function (
     debounce,
     dedupe,
     deps,
+    fork: patchFork,
     graceful_ipc: gracefulIPC,
     ignore,
     interval,
     notify: notifyEnabled,
     poll: forcePolling,
     respawn,
-    timestamp
+    timestamp,
+    vm: patchVm,
+    worker: patchWorker
   }
 ) {
   if (!script) {
@@ -52,9 +58,6 @@ module.exports = function (
   const isIgnored = configureIgnore(ignore);
   const isTooDeep = configureDeps(deps);
 
-  // Run ./dedupe.js as preload script
-  if (dedupe) process.env.NODE_DEV_PRELOAD = require.resolve('./dedupe');
-
   const watcher = filewatcher({ debounce, forcePolling, interval });
   let isPaused = false;
 
@@ -89,20 +92,25 @@ module.exports = function (
   function start() {
     isPaused = false;
 
-    const args = nodeArgs.slice();
+    const execArgv = nodeArgs.slice();
 
-    args.push(`--require=${require.resolve('./wrap')}`);
+    execArgv.push(`--require=${resolveHook('suppress-experimental-warnings')}`);
+    if (dedupe) execArgv.push(`--require=${resolveHook('dedupe')}`);
+    execArgv.push(`--require=${resolveHook('patch')}`);
+    if (patchFork) execArgv.push(`--require=${resolveHook('patch-fork')}`);
+    if (patchVm) execArgv.push(`--require=${resolveHook('patch-vm')}`);
+    if (patchWorker) execArgv.push(`--require=${resolveHook('patch-worker')}`);
 
     const loaderName = semver.satisfies(process.version, '>=16.12.0') ? 'load' : 'get-format';
 
-    const loaderURL = pathToFileURL(require.resolve(`./loaders/${loaderName}.mjs`));
+    const loaderURL = new URL(`./loaders/${loaderName}.mjs`, import.meta.url);
 
-    args.push(`--experimental-loader=${loaderURL.href}`);
+    execArgv.push(`--experimental-loader=${loaderURL.href}`);
 
     child = fork(script, scriptArgs, {
       cwd: process.cwd(),
       env: process.env,
-      execArgv: args
+      execArgv
     });
 
     if (respawn) {
@@ -155,4 +163,4 @@ module.exports = function (
 
   clearOutput();
   start();
-};
+}
diff --git a/lib/ipc.cjs b/lib/ipc.cjs
new file mode 100644
index 0000000..96a4fa3
--- /dev/null
+++ b/lib/ipc.cjs
@@ -0,0 +1,52 @@
+const { once } = require('events');
+const { Worker } = require('worker_threads');
+
+const logFactory = require('./log.cjs');
+
+const cmd = 'NODE_DEV';
+const log = logFactory({});
+let nodeDevPort;
+
+exports.on = (src, prop, cb) => {
+  src.on('internalMessage', m => {
+    if (m.cmd === cmd && prop in m) cb(m);
+  });
+};
+
+exports.relay = src => {
+  if (src instanceof Worker) {
+    // create a separate message channel for node-dev
+    const { port1, port2 } = new MessageChannel();
+    port1.unref();
+    port1.on('message', exports.send);
+    src.postMessage({ cmd, port: port2 }, [port2]);
+  } else {
+    src.on('internalMessage', m => {
+      if (process.connected && m.cmd === cmd) process.send(m);
+    });
+  }
+};
+
+exports.send = m => {
+  if (process.connected) {
+    process.send({ ...m, cmd });
+  } else if (nodeDevPort) {
+    // this has doesn't seem to have a race condition in testing
+    // but just in case, the log statement below should notify of it
+    nodeDevPort.postMessage({ ...m, cmd });
+  } else {
+    log.warn(
+      `node-dev: The module ${m.required} was imported from an orphaned child process or worker thread`
+    );
+  }
+};
+
+exports.receiveMessagePort = async src => {
+  // the first message received by this thread should contain the parent port
+  const [m] = await once(src, 'message');
+  if (m && m.cmd === cmd) {
+    nodeDevPort = m.port;
+  } else {
+    log.warn('node-dev: unexpected message on the parentPort', m);
+  }
+};
diff --git a/lib/ipc.js b/lib/ipc.js
index c37ab44..13dd097 100644
--- a/lib/ipc.js
+++ b/lib/ipc.js
@@ -1,4 +1,11 @@
+const { once } = require('events');
+const { MessageChannel, Worker } = require('worker_threads');
+
+const logFactory = require('./log.cjs');
+
+let nodeDevPort;
 const cmd = 'NODE_DEV';
+const log = logFactory({});
 
 exports.on = (src, prop, cb) => {
   src.on('internalMessage', m => {
@@ -7,11 +14,39 @@ exports.on = (src, prop, cb) => {
 };
 
 exports.relay = src => {
-  src.on('internalMessage', m => {
-    if (process.connected && m.cmd === cmd) process.send(m);
-  });
+  if (src instanceof Worker) {
+    // create a separate message channel for node-dev
+    const { port1, port2 } = new MessageChannel();
+    port1.unref();
+    port1.on('message', exports.send);
+    src.postMessage({ cmd, port: port2 }, [port2]);
+  } else {
+    src.on('internalMessage', m => {
+      if (process.connected && m.cmd === cmd) process.send(m);
+    });
+  }
 };
 
 exports.send = m => {
-  if (process.connected) process.send({ ...m, cmd });
+  if (nodeDevPort) {
+    // this has doesn't seem to have a race condition in testing
+    // but just in case, the log statement below should notify of it
+    nodeDevPort.postMessage({ ...m, cmd });
+  } else if (process.connected) {
+    process.send({ ...m, cmd });
+  } else {
+    log.warn(
+      `node-dev: The module ${m.required} was imported from an orphaned child process or worker thread`
+    );
+  }
+};
+
+exports.receiveMessagePort = async src => {
+  // the first message received by this thread should contain the parent port
+  const [m] = await once(src, 'message');
+  if (m && m.cmd === cmd) {
+    nodeDevPort = m.port;
+  } else {
+    log.warn('node-dev: unexpected message on the parentPort', m);
+  }
 };
diff --git a/lib/loaders/get-format.mjs b/lib/loaders/get-format.mjs
index 8e72a4a..5940a3c 100644
--- a/lib/loaders/get-format.mjs
+++ b/lib/loaders/get-format.mjs
@@ -1,6 +1,6 @@
 import { createRequire } from 'module';
 import { fileURLToPath } from 'url';
-import { send } from './ipc.mjs';
+import { send } from '../ipc.cjs';
 
 const require = createRequire(import.meta.url);
 
diff --git a/lib/loaders/ipc.mjs b/lib/loaders/ipc.mjs
deleted file mode 100644
index 61c48c4..0000000
--- a/lib/loaders/ipc.mjs
+++ /dev/null
@@ -1,5 +0,0 @@
-const cmd = 'NODE_DEV';
-
-export const send = m => {
-  if (process.connected) process.send({ ...m, cmd });
-};
diff --git a/lib/loaders/load.mjs b/lib/loaders/load.mjs
index 2772f60..90909d5 100644
--- a/lib/loaders/load.mjs
+++ b/lib/loaders/load.mjs
@@ -1,6 +1,6 @@
 import { createRequire } from 'module';
 import { fileURLToPath } from 'url';
-import { send } from './ipc.mjs';
+import { send } from '../ipc.cjs';
 
 const require = createRequire(import.meta.url);
 
diff --git a/lib/log.js b/lib/log.cjs
similarity index 100%
rename from lib/log.js
rename to lib/log.cjs
diff --git a/lib/notify.js b/lib/notify.js
index aadd579..7d525c1 100644
--- a/lib/notify.js
+++ b/lib/notify.js
@@ -1,9 +1,11 @@
-const notifier = require('node-notifier');
+import notifier from 'node-notifier';
+import { fileURLToPath } from 'url';
 
-const iconLevelPath = level => require.resolve(`../icons/node_${level}.png`);
+const iconLevelPath = level =>
+  fileURLToPath(new URL(`../icons/node_${level}.png`, import.meta.url));
 
 // Writes a message to the console and optionally displays a desktop notification.
-module.exports = (notifyEnabled, log) => {
+export default (notifyEnabled, log) => {
   return (title = 'node-dev', message, level = 'info') => {
     log[level](`${title}: ${message}`);
 
diff --git a/lib/dedupe.js b/lib/require/dedupe.js
similarity index 100%
rename from lib/dedupe.js
rename to lib/require/dedupe.js
diff --git a/lib/require/package.json b/lib/require/package.json
new file mode 100644
index 0000000..c9a4422
--- /dev/null
+++ b/lib/require/package.json
@@ -0,0 +1,3 @@
+{
+  "type": "commonjs"
+}
\ No newline at end of file
diff --git a/lib/require/patch-fork.js b/lib/require/patch-fork.js
new file mode 100644
index 0000000..b210da2
--- /dev/null
+++ b/lib/require/patch-fork.js
@@ -0,0 +1,11 @@
+const childProcess = require('child_process');
+const { relay } = require('../ipc.cjs');
+
+// Overwrite child_process.fork() so that we can hook into forked processes
+// too. We also need to relay messages about required files to the parent.
+const { fork } = childProcess;
+childProcess.fork = (modulePath, args, options) => {
+  const child = fork(modulePath, args, options);
+  relay(child);
+  return child;
+};
diff --git a/lib/require/patch-vm.js b/lib/require/patch-vm.js
new file mode 100644
index 0000000..6d0aa93
--- /dev/null
+++ b/lib/require/patch-vm.js
@@ -0,0 +1,25 @@
+const vm = require('vm');
+const { send } = require('../ipc.cjs');
+
+patch(vm, 'createScript', 1);
+patch(vm, 'runInThisContext', 1);
+patch(vm, 'runInNewContext', 2);
+patch(vm, 'runInContext', 2);
+
+/**
+ * Patch the specified method to watch the file at the given argument
+ * index.
+ */
+function patch(obj, method, optionsArgIndex) {
+  const orig = obj[method];
+  if (!orig) return;
+  obj[method] = function () {
+    const opts = arguments[optionsArgIndex];
+    let file = null;
+    if (opts) {
+      file = typeof opts === 'string' ? opts : opts.filename;
+    }
+    if (file) send({ required: file });
+    return orig.apply(this, arguments);
+  };
+}
diff --git a/lib/require/patch-worker.js b/lib/require/patch-worker.js
new file mode 100644
index 0000000..1e95a26
--- /dev/null
+++ b/lib/require/patch-worker.js
@@ -0,0 +1,14 @@
+const workerThreads = require('worker_threads');
+const { receiveMessagePort, relay } = require('../ipc.cjs');
+
+const { Worker } = workerThreads;
+workerThreads.Worker = class NodeDevWorker extends Worker {
+  constructor(...args) {
+    super(...args);
+    relay(this);
+  }
+};
+
+if (workerThreads.parentPort) {
+  receiveMessagePort(workerThreads.parentPort);
+}
diff --git a/lib/require/patch.js b/lib/require/patch.js
new file mode 100644
index 0000000..c9802f7
--- /dev/null
+++ b/lib/require/patch.js
@@ -0,0 +1,77 @@
+const { Module } = require('module');
+const { dirname, extname } = require('path');
+const { isMainThread, getEnvironmentData, setEnvironmentData } = require('worker_threads');
+const { getConfig } = require('../cfg.cjs');
+const { send } = require('../ipc.cjs');
+
+// Error handler that displays a notification and logs the stack to stderr:
+process.on('uncaughtException', err => {
+  // Sometimes uncaught exceptions are not errors
+  const { message, name, stack } =
+    err instanceof Error ? err : new Error(`uncaughtException ${err}`);
+
+  console.error(stack);
+
+  // If there's a custom uncaughtException handler expect it to terminate
+  // the process.
+  const willTerminate = process.listenerCount('uncaughtException') > 1;
+
+  send({ error: name, message, willTerminate });
+});
+
+if (isMainThread) {
+  // When using worker threads, each thread inherits execArgv and re-evaulates
+  // --require scripts. Worker threads do not inherit argv, so we copy argv[1]
+  // to the environment for those processes to use.
+  setEnvironmentData('NODE_DEV_SCRIPT', require.resolve(process.argv[1]));
+}
+
+const script = getEnvironmentData('NODE_DEV_SCRIPT');
+
+// Check if a module is registered for this extension
+const ext = extname(script).slice(1);
+const { extensions } = getConfig(script);
+
+const register = extensions[ext];
+
+// Support extensions where 'require' returns a function that accepts options
+if (typeof register === 'object' && register.name) {
+  const fn = require(require.resolve(register.name, { paths: [dirname(script)] }));
+  if (typeof fn === 'function' && register.options) {
+    // require returned a function, call it with options
+    fn(register.options);
+  }
+} else if (typeof register === 'string') {
+  require(require.resolve(register, { paths: [dirname(script)] }));
+}
+
+// Hook into Node's `require(...)`
+updateHooks();
+
+/**
+ * (Re-)install hooks for all registered file extensions.
+ */
+function updateHooks() {
+  Object.keys(Module._extensions).forEach(ext => {
+    const fn = Module._extensions[ext];
+    if (typeof fn === 'function' && fn.name !== 'nodeDevHook') {
+      Module._extensions[ext] = createHook(fn);
+    }
+  });
+}
+
+/**
+ * Returns a function that can be put into `require.extensions` in order to
+ * invoke the callback when a module is required for the first time.
+ */
+function createHook(handler) {
+  return function nodeDevHook(module, filename) {
+    if (!module.loaded) send({ required: module.filename });
+
+    // Invoke the original handler
+    handler(module, filename);
+
+    // Make sure the module did not hijack the handler
+    updateHooks();
+  };
+}
diff --git a/lib/require/suppress-experimental-warnings.js b/lib/require/suppress-experimental-warnings.js
new file mode 100644
index 0000000..5de3583
--- /dev/null
+++ b/lib/require/suppress-experimental-warnings.js
@@ -0,0 +1,23 @@
+// Source: https://github.com/nodejs/node/issues/30810#issue-533506790
+
+const { emitWarning, emit } = process;
+
+process.emitWarning = (warning, ...args) => {
+  if (args[0] === 'ExperimentalWarning') {
+    return;
+  }
+
+  if (args[0] && typeof args[0] === 'object' && args[0].type === 'ExperimentalWarning') {
+    return;
+  }
+
+  return emitWarning(warning, ...args);
+};
+
+process.emit = (...args) => {
+  if (args[1]?.name === 'ExperimentalWarning') {
+    return;
+  }
+
+  return emit.call(process, ...args);
+};
diff --git a/lib/suppress-experimental-warnings.js b/lib/suppress-experimental-warnings.js
deleted file mode 100644
index a881277..0000000
--- a/lib/suppress-experimental-warnings.js
+++ /dev/null
@@ -1,25 +0,0 @@
-// Source: https://github.com/nodejs/node/issues/30810#issue-533506790
-
-module.exports = p => {
-  const { emitWarning, emit } = p;
-
-  p.emitWarning = (warning, ...args) => {
-    if (args[0] === 'ExperimentalWarning') {
-      return;
-    }
-
-    if (args[0] && typeof args[0] === 'object' && args[0].type === 'ExperimentalWarning') {
-      return;
-    }
-
-    return emitWarning(warning, ...args);
-  };
-
-  p.emit = (...args) => {
-    if (args[1]?.name === 'ExperimentalWarning') {
-      return;
-    }
-
-    return emit.call(p, ...args);
-  };
-};
diff --git a/lib/wrap.js b/lib/wrap.js
deleted file mode 100755
index 71d1a63..0000000
--- a/lib/wrap.js
+++ /dev/null
@@ -1,71 +0,0 @@
-const { dirname, extname } = require('path');
-const childProcess = require('child_process');
-const { isMainThread } = require('worker_threads');
-
-const { getConfig } = require('./cfg');
-const hook = require('./hook');
-const { relay, send } = require('./ipc');
-const suppressExperimentalWarnings = require('./suppress-experimental-warnings');
-
-// Experimental warnings need to be suppressed in worker threads as well, since
-// their process inherits the Node arguments from the main thread.
-suppressExperimentalWarnings(process);
-
-// When using worker threads, each thread appears to require this file through
-// the shared Node arguments (--require), so filter them out here and only run
-// on the main thread.
-if (!isMainThread) return;
-
-const script = require.resolve(process.argv[1]);
-const { extensions, fork, vm } = getConfig(script);
-
-if (process.env.NODE_DEV_PRELOAD) {
-  require(process.env.NODE_DEV_PRELOAD);
-}
-
-// We want to exit on SIGTERM, but defer to existing SIGTERM handlers.
-process.once('SIGTERM', () => process.listenerCount('SIGTERM') || process.exit(0));
-
-if (fork) {
-  // Overwrite child_process.fork() so that we can hook into forked processes
-  // too. We also need to relay messages about required files to the parent.
-  const originalFork = childProcess.fork;
-  childProcess.fork = (modulePath, args, options) => {
-    const child = originalFork(modulePath, args, options);
-    relay(child);
-    return child;
-  };
-}
-
-// Error handler that displays a notification and logs the stack to stderr:
-process.on('uncaughtException', err => {
-  // Sometimes uncaught exceptions are not errors
-  const { message, name, stack } =
-    err instanceof Error ? err : new Error(`uncaughtException ${err}`);
-
-  console.error(stack);
-
-  // If there's a custom uncaughtException handler expect it to terminate
-  // the process.
-  const willTerminate = process.listenerCount('uncaughtException') > 1;
-
-  send({ error: name, message, willTerminate });
-});
-
-// Hook into require() and notify the parent process about required files
-hook(vm, required => send({ required }));
-
-// Check if a module is registered for this extension
-const ext = extname(script).slice(1);
-const mod = extensions[ext];
-
-// Support extensions where 'require' returns a function that accepts options
-if (typeof mod === 'object' && mod.name) {
-  const fn = require(require.resolve(mod.name, { paths: [dirname(script)] }));
-  if (typeof fn === 'function' && mod.options) {
-    // require returned a function, call it with options
-    fn(mod.options);
-  }
-} else if (typeof mod === 'string') {
-  require(require.resolve(mod, { paths: [dirname(script)] }));
-}
diff --git a/package.json b/package.json
index 15cdda9..36521b6 100644
--- a/package.json
+++ b/package.json
@@ -19,15 +19,24 @@
     "url": "http://github.com/fgnass/node-dev.git"
   },
   "license": "MIT",
+  "type": "module",
   "bin": {
-    "node-dev": "bin/node-dev"
+    "node-dev": "bin/node-dev.js"
   },
   "main": "./lib",
+  "exports": {
+    ".": "./lib/index.js",
+    "./package.json": "./package.json"
+  },
+  "files": [
+    "icons/",
+    "lib/"
+  ],
   "engines": {
     "node": ">=14"
   },
   "scripts": {
-    "lint": "eslint lib test bin/node-dev",
+    "lint": "eslint lib test bin",
     "test": "node test",
     "prepare": "husky install"
   },
@@ -54,7 +63,7 @@
     "typescript": "^4.6.3"
   },
   "lint-staged": {
-    "*.{js,mjs}": "eslint --cache --fix",
-    "*.{js,md}": "prettier --write"
+    "*.{js,cjs,mjs}": "eslint --cache --fix",
+    "*.{js,cjs,mjs,md}": "prettier --write"
   }
 }
\ No newline at end of file
diff --git a/test/cli.js b/test/cli.js
index 64bfa4d..a708151 100644
--- a/test/cli.js
+++ b/test/cli.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const cli = require('../lib/cli.js');
+import cli from '../lib/cli.js';
 
 tap.test('notify is enabled by default', t => {
   const {
diff --git a/test/fixture/package.json b/test/fixture/package.json
new file mode 100644
index 0000000..c9a4422
--- /dev/null
+++ b/test/fixture/package.json
@@ -0,0 +1,3 @@
+{
+  "type": "commonjs"
+}
\ No newline at end of file
diff --git a/test/index.js b/test/index.js
index d34e931..f2daba2 100644
--- a/test/index.js
+++ b/test/index.js
@@ -1,4 +1,4 @@
-require('./cli');
-require('./log');
-require('./run');
-require('./spawn');
+import './cli.js';
+import './log.js';
+import './run.js';
+import './spawn/index.js';
diff --git a/test/log.js b/test/log.js
index 8fc1c4c..9524f94 100644
--- a/test/log.js
+++ b/test/log.js
@@ -1,7 +1,7 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { defaultConfig } = require('../lib/cfg');
-const logFactory = require('../lib/log');
+import { defaultConfig } from '../lib/cfg.cjs';
+import logFactory from '../lib/log.cjs';
 
 const noColorCfg = { ...defaultConfig, noColor: true };
 
diff --git a/test/run.js b/test/run.js
index b41d5ca..bbe94d1 100644
--- a/test/run.js
+++ b/test/run.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn, touchFile } = require('./utils');
+import { spawn, touchFile } from './utils.js';
 
 const run = (cmd, exit) => {
   return spawn(cmd, out => {
diff --git a/test/spawn/argv.js b/test/spawn/argv.js
index e534e38..87a5086 100644
--- a/test/spawn/argv.js
+++ b/test/spawn/argv.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn } = require('../utils');
+import { spawn } from '../utils.js';
 
 tap.test('should not show up in argv', t => {
   spawn('argv.js foo', out => {
diff --git a/test/spawn/caught.js b/test/spawn/caught.js
index 5226fde..d55b378 100644
--- a/test/spawn/caught.js
+++ b/test/spawn/caught.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn } = require('../utils');
+import { spawn } from '../utils.js';
 
 tap.test('should ignore caught errors', t => {
   spawn('catch-no-such-module.js', out => {
diff --git a/test/spawn/clear.js b/test/spawn/clear.js
index 718d9fa..4222723 100644
--- a/test/spawn/clear.js
+++ b/test/spawn/clear.js
@@ -1,8 +1,8 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn, touchFile } = require('../utils');
+import { spawn, touchFile } from '../utils.js';
 
-const { control } = require('../../lib/clear');
+import { control } from '../../lib/clear.js';
 
 const reClear = new RegExp(control);
 
diff --git a/test/spawn/cli-require.js b/test/spawn/cli-require.js
index ac84963..d2375ad 100644
--- a/test/spawn/cli-require.js
+++ b/test/spawn/cli-require.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn, touchFile } = require('../utils');
+import { spawn, touchFile } from '../utils.js';
 
 tap.test('Supports require from the command-line (ts-node/register)', t => {
   spawn('--require=ts-node/register typescript/index.ts', out => {
diff --git a/test/spawn/cluster.js b/test/spawn/cluster.js
index c616a19..bcc9b31 100644
--- a/test/spawn/cluster.js
+++ b/test/spawn/cluster.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn, touchFile } = require('../utils');
+import { spawn, touchFile } from '../utils.js';
 
 tap.test('Restart the cluster', t => {
   if (process.platform === 'win32') {
diff --git a/test/spawn/conceal.js b/test/spawn/conceal.js
index afd2c89..0686a59 100644
--- a/test/spawn/conceal.js
+++ b/test/spawn/conceal.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn } = require('../utils');
+import { spawn } from '../utils.js';
 
 tap.test('should conceal the wrapper', t => {
   // require.main should be main.js not wrap.js!
diff --git a/test/spawn/errors.js b/test/spawn/errors.js
index 1c4d47f..6861736 100644
--- a/test/spawn/errors.js
+++ b/test/spawn/errors.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn, touchFile } = require('../utils');
+import { spawn, touchFile } from '../utils.js';
 
 tap.test('should handle errors', t => {
   spawn('error.js', out => {
diff --git a/test/spawn/esmodule.js b/test/spawn/esmodule.js
index 1b6b816..ae122e1 100644
--- a/test/spawn/esmodule.js
+++ b/test/spawn/esmodule.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn, touchFile } = require('../utils');
+import { spawn, touchFile } from '../utils.js';
 
 tap.test('Supports ECMAScript modules with experimental-specifier-resolution', t => {
   spawn('--experimental-specifier-resolution=node resolution.mjs', out => {
diff --git a/test/spawn/exit-code.js b/test/spawn/exit-code.js
index b399c0e..c89b607 100644
--- a/test/spawn/exit-code.js
+++ b/test/spawn/exit-code.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn } = require('../utils');
+import { spawn } from '../utils.js';
 
 tap.test('should pass through the exit code', t => {
   spawn('exit.js').on('exit', code => {
diff --git a/test/spawn/experimental-warnings.js b/test/spawn/experimental-warnings.js
index 2b3956a..aeee183 100644
--- a/test/spawn/experimental-warnings.js
+++ b/test/spawn/experimental-warnings.js
@@ -1,5 +1,5 @@
-const tap = require('tap');
-const { spawn } = require('../utils');
+import tap from 'tap';
+import { spawn } from '../utils.js';
 
 tap.test('Should suppress experimental warning spam', t => {
   spawn('env.js', out => {
diff --git a/test/spawn/expose-gc.js b/test/spawn/expose-gc.js
index ccecf8d..317f3a4 100644
--- a/test/spawn/expose-gc.js
+++ b/test/spawn/expose-gc.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn } = require('../utils');
+import { spawn } from '../utils.js';
 
 tap.test('should pass unknown args to node binary', t => {
   spawn('--expose_gc gc.js foo', out => {
diff --git a/test/spawn/extension-options.js b/test/spawn/extension-options.js
index 49cd5d2..36a35b1 100644
--- a/test/spawn/extension-options.js
+++ b/test/spawn/extension-options.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn } = require('../utils');
+import { spawn } from '../utils.js';
 
 tap.test('should pass options to extensions according to .node-dev.json', t => {
   spawn('extension-options', out => {
diff --git a/test/spawn/graceful-ipc.js b/test/spawn/graceful-ipc.js
index d8e9d4d..0aa06de 100644
--- a/test/spawn/graceful-ipc.js
+++ b/test/spawn/graceful-ipc.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn, touchFile } = require('../utils');
+import { spawn, touchFile } from '../utils.js';
 
 tap.test('should send IPC message when configured', t => {
   spawn('--graceful_ipc=node-dev:restart ipc-server.js', out => {
diff --git a/test/spawn/index.js b/test/spawn/index.js
index fce6975..e345686 100644
--- a/test/spawn/index.js
+++ b/test/spawn/index.js
@@ -1,24 +1,24 @@
-require('./argv');
-require('./caught');
-require('./clear');
-require('./cli-require');
-require('./cluster');
-require('./conceal');
-require('./errors');
-require('./esmodule');
-require('./exit-code');
-require('./experimental-warnings');
-require('./expose-gc');
-require('./extension-options');
-require('./graceful-ipc');
-require('./inspect');
-require('./kill-fork');
-require('./no-such-module');
-require('./node-env');
-require('./relay-stdin');
-require('./require-extensions');
-require('./restart-twice');
-require('./sigterm');
-require('./timestamps');
-require('./typescript');
-require('./uncaught');
+import './argv.js';
+import './caught.js';
+import './clear.js';
+import './cli-require.js';
+import './cluster.js';
+import './conceal.js';
+import './errors.js';
+import './esmodule.js';
+import './exit-code.js';
+import './experimental-warnings.js';
+import './expose-gc.js';
+import './extension-options.js';
+import './graceful-ipc.js';
+import './inspect.js';
+import './kill-fork.js';
+import './no-such-module.js';
+import './node-env.js';
+import './relay-stdin.js';
+import './require-extensions.js';
+import './restart-twice.js';
+import './sigterm.js';
+import './timestamps.js';
+import './typescript.js';
+import './uncaught.js';
diff --git a/test/spawn/inspect.js b/test/spawn/inspect.js
index 8a7b587..fc194c4 100644
--- a/test/spawn/inspect.js
+++ b/test/spawn/inspect.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn, touchFile } = require('../utils');
+import { spawn, touchFile } from '../utils.js';
 
 tap.test('Supports --inspect', t => {
   spawn('--inspect server.js', out => {
diff --git a/test/spawn/kill-fork.js b/test/spawn/kill-fork.js
index aa7825a..a836136 100644
--- a/test/spawn/kill-fork.js
+++ b/test/spawn/kill-fork.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn } = require('../utils');
+import { spawn } from '../utils.js';
 
 tap.test('should kill the forked processes', t => {
   spawn('pid.js', out => {
diff --git a/test/spawn/no-such-module.js b/test/spawn/no-such-module.js
index e17bb75..fa29641 100644
--- a/test/spawn/no-such-module.js
+++ b/test/spawn/no-such-module.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn } = require('../utils');
+import { spawn } from '../utils.js';
 
 tap.test('should watch if no such module', t => {
   let passed = false;
diff --git a/test/spawn/node-env.js b/test/spawn/node-env.js
index 33e6f54..13d81b5 100644
--- a/test/spawn/node-env.js
+++ b/test/spawn/node-env.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn } = require('../utils');
+import { spawn } from '../utils.js';
 
 tap.test('should *not* set NODE_ENV', t => {
   spawn('env.js', out => {
diff --git a/test/spawn/relay-stdin.js b/test/spawn/relay-stdin.js
index 4a6aba3..3ddaf80 100644
--- a/test/spawn/relay-stdin.js
+++ b/test/spawn/relay-stdin.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn } = require('../utils');
+import { spawn } from '../utils.js';
 
 tap.test('should relay stdin', t => {
   spawn('echo.js', out => {
diff --git a/test/spawn/require-extensions.js b/test/spawn/require-extensions.js
index d344435..2294de3 100644
--- a/test/spawn/require-extensions.js
+++ b/test/spawn/require-extensions.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn } = require('../utils');
+import { spawn } from '../utils.js';
 
 tap.test('should be resistant to breaking `require.extensions`', t => {
   spawn('modify-extensions.js', out => {
diff --git a/test/spawn/restart-twice.js b/test/spawn/restart-twice.js
index c87d67d..d1f1510 100644
--- a/test/spawn/restart-twice.js
+++ b/test/spawn/restart-twice.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn, touchFile } = require('../utils');
+import { spawn, touchFile } from '../utils.js';
 
 tap.test('should restart the server twice', t => {
   spawn('server.js', out => {
diff --git a/test/spawn/sigterm.js b/test/spawn/sigterm.js
index ed229d8..5025cd5 100644
--- a/test/spawn/sigterm.js
+++ b/test/spawn/sigterm.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn, touchFile } = require('../utils');
+import { spawn, touchFile } from '../utils.js';
 
 tap.test('should allow graceful shutdowns', t => {
   if (process.platform === 'win32') {
diff --git a/test/spawn/timestamps.js b/test/spawn/timestamps.js
index 8105693..f58beb4 100644
--- a/test/spawn/timestamps.js
+++ b/test/spawn/timestamps.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn, touchFile } = require('../utils');
+import { spawn, touchFile } from '../utils.js';
 
 tap.test('Logs timestamp by default', t => {
   spawn('server.js', out => {
diff --git a/test/spawn/typescript.js b/test/spawn/typescript.js
index 49238da..03e8e53 100644
--- a/test/spawn/typescript.js
+++ b/test/spawn/typescript.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn, touchFile } = require('../utils');
+import { spawn, touchFile } from '../utils.js';
 
 tap.test('Uses ts-node/register for .ts files through config file (also the default)', t => {
   spawn('typescript/index.ts', out => {
diff --git a/test/spawn/uncaught.js b/test/spawn/uncaught.js
index 0930a57..ad7fdc9 100644
--- a/test/spawn/uncaught.js
+++ b/test/spawn/uncaught.js
@@ -1,6 +1,6 @@
-const tap = require('tap');
+import tap from 'tap';
 
-const { spawn } = require('../utils');
+import { spawn } from '../utils.js';
 
 tap.test('should run async code uncaughtException handlers', t => {
   spawn('uncaught-exception-handler.js', out => {
diff --git a/test/utils.js b/test/utils.js
index b16e843..ae7dc05 100644
--- a/test/utils.js
+++ b/test/utils.js
@@ -1,18 +1,21 @@
-const { spawn } = require('child_process');
-const { join } = require('path');
-const touch = require('touch');
+import { spawn as _spawn } from 'child_process';
+import { join } from 'path';
+import touch from 'touch';
+import { fileURLToPath } from 'url';
 
-const { control } = require('../lib/clear');
+import { control } from '../lib/clear.js';
 
-const bin = join(__dirname, '..', 'bin', 'node-dev');
-const dir = join(__dirname, 'fixture');
+const bin = fileURLToPath(new URL('../bin/node-dev.js', import.meta.url));
+const dir = fileURLToPath(new URL('fixture', import.meta.url));
 
 const reClear = new RegExp(control);
 
-const noop = () => {/**/};
+const noop = () => {
+  /**/
+};
 
-exports.spawn = (cmd, cb = noop) => {
-  const ps = spawn('node', [bin].concat(cmd.split(' ')), { cwd: dir });
+export function spawn(cmd, cb = noop) {
+  const ps = _spawn('node', [bin].concat(cmd.split(' ')), { cwd: dir });
   let err = '';
 
   function errorHandler(data) {
@@ -50,12 +53,12 @@ exports.spawn = (cmd, cb = noop) => {
   ps.stdout.on('data', outHandler);
 
   return ps;
-};
+}
 
 // filewatcher requires a new mtime to trigger a change event
 // but most file systems only have second precision, so wait
 // one full second before touching.
 
-exports.touchFile = (...filepath) => {
+export function touchFile(...filepath) {
   setTimeout(() => touch(join(dir, ...filepath)), 1000);
-};
+}