async-exit-hook 2.0.1: hookEvent

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify async-exit-hook.hookEvent in pkg:npm/async-exit-hook@2.0.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/async-exit-hook@2.0.1
Demonstrate these symbols/APIs:
  - async-exit-hook.hookEvent

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:64db19f4f0ea5fcb637a7414c4790d83116f16cc47828f177384e5d3fb290330","contract":["assert hookEvent is a function exported by async-exit-hook","assert hookEvent registers custom event name in hookedEvents list","assert hookEvent triggers registered exit hooks and exits with specified code when event is emitted","assert hookEvent with filter suppresses exit and hooks when filter returns true","assert hookEvent with filter executes hooks and exits when filter returns false","assert unhookEvent removes the event handler and prevents hooks from executing","assert hookEvent supports asynchronous exit hooks before process termination"],"goal":"verify async-exit-hook.hookEvent in pkg:npm/async-exit-hook@2.0.1","kind":"HOW","packages":["pkg:npm/async-exit-hook@2.0.1"],"schemaVersion":1,"symbols":["async-exit-hook.hookEvent"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/async-exit-hook@2.0.1"],"schemaVersion":1,"subject":"pkg:npm/async-exit-hook@2.0.1","symbols":["async-exit-hook.hookEvent"],"verifierAdapter":"node-typescript@1"}

'use strict';

const exitHook = require('async-exit-hook');

/**
 * Hook a custom signal or event to trigger exit hooks.
 * @param {string} event - Event name to listen on process.
 * @param {number} [code] - Exit code to terminate with.
 * @param {Function} [filter] - Optional filter function. If returns true, exit is aborted.
 */
function hookEvent(event, code, filter) {
  exitHook.hookEvent(event, code, filter);
}

/**
 * Unhook a previously hooked event.
 * @param {string} event - Event name to remove.
 */
function unhookEvent(event) {
  exitHook.unhookEvent(event);
}

/**
 * List all currently hooked events.
 * @returns {string[]} Array of hooked event names.
 */
function hookedEvents() {
  return exitHook.hookedEvents();
}

/**
 * Register an exit hook (synchronous or asynchronous).
 * @param {Function} hook - Hook function.
 */
function registerExitHook(hook) {
  exitHook(hook);
}

module.exports = {
  exitHook,
  hookEvent,
  unhookEvent,
  hookedEvents,
  registerExitHook,
};

{
  "name": "sample-async-exit-hook",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-async-exit-hook",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "async-exit-hook": "2.0.1"
      }
    },
    "node_modules/async-exit-hook": {
      "version": "2.0.1",
      "resolved": "https://registry.npmjs.org/async-exit-hook/-/async-exit-hook-2.0.1.tgz",
      "integrity": "sha512-NW2cX8m1Q7KPA7a5M2ULQeZ2wR5qI5PAbw5L0UOMxdioVk9PMZ0h1TmyZEkPYrCvYjDlFICusOu1dlEKAAeXBw==",
      "license": "MIT",
      "engines": {
        "node": ">=0.12.0"
      }
    }
  }
}

{
  "name": "sample-async-exit-hook",
  "version": "1.0.0",
  "description": "Clean-room sample verifying async-exit-hook.hookEvent in async-exit-hook",
  "main": "index.js",
  "license": "MIT-0",
  "dependencies": {
    "async-exit-hook": "2.0.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify async-exit-hook.hookEvent in pkg:npm/async-exit-hook@2.0.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/async-exit-hook@2.0.1"
  ],
  "symbols": [
    "async-exit-hook.hookEvent"
  ]
}

import assert from 'node:assert';
import { execFileSync } from 'node:child_process';
import exitHook from 'async-exit-hook';
import {
  exitHook as importedHook,
  hookEvent,
  unhookEvent,
  hookedEvents,
  registerExitHook,
} from '../index.js';

// 1. assert hookEvent is a function exported by async-exit-hook
assert.strictEqual(typeof exitHook.hookEvent, 'function', 'exitHook.hookEvent must be a function');
assert.strictEqual(typeof hookEvent, 'function', 'hookEvent from index.js must be a function');
assert.strictEqual(typeof unhookEvent, 'function', 'unhookEvent from index.js must be a function');
assert.strictEqual(typeof hookedEvents, 'function', 'hookedEvents from index.js must be a function');
assert.strictEqual(typeof registerExitHook, 'function', 'registerExitHook from index.js must be a function');
assert.strictEqual(importedHook, exitHook, 'imported exitHook must match package export');

// 2. assert hookEvent registers custom event name in hookedEvents list
hookEvent('customTestEvent', 0);
assert.ok(hookedEvents().includes('customTestEvent'), 'hookedEvents must include customTestEvent');
unhookEvent('customTestEvent');
assert.ok(!hookedEvents().includes('customTestEvent'), 'hookedEvents must not include unhooked event');

// 3. assert hookEvent triggers registered exit hooks and exits with specified code when event is emitted
const childTriggerCode = `
  const exitHook = require('async-exit-hook');
  exitHook(() => {
    console.log('CUSTOM_HOOK_TRIGGERED');
  });
  exitHook.hookEvent('myCustomSignal', 42);
  process.emit('myCustomSignal');
`;

let customExitThrew = false;
try {
  execFileSync(process.execPath, ['-e', childTriggerCode], { encoding: 'utf8', timeout: 5000 });
} catch (err) {
  customExitThrew = true;
  assert.strictEqual(err.status, 42, 'Process should exit with code 42');
  assert.match(err.stdout || '', /CUSTOM_HOOK_TRIGGERED/, 'Exit hook should have run');
}
assert.strictEqual(customExitThrew, true, 'Custom event with code 42 should have exited non-zero');

// 4. assert hookEvent with filter suppresses exit and hooks when filter returns true
// 5. assert hookEvent with filter executes hooks and exits when filter returns false
const childFilterCode = `
  const exitHook = require('async-exit-hook');
  let filterHookCount = 0;
  exitHook.hookEvent('filteredEvent', 33, (msg) => msg !== 'trigger');
  exitHook(() => {
    filterHookCount++;
    console.log('HOOK_CALLED_COUNT:' + filterHookCount);
  });

  process.emit('filteredEvent', 'ignore');
  console.log('AFTER_IGNORE_COUNT:' + filterHookCount);

  process.emit('filteredEvent', 'trigger');
`;

let filterTriggerThrew = false;
try {
  execFileSync(process.execPath, ['-e', childFilterCode], { encoding: 'utf8', timeout: 5000 });
} catch (err) {
  filterTriggerThrew = true;
  assert.strictEqual(err.status, 33, 'Process should exit with code 33');
  assert.match(err.stdout || '', /AFTER_IGNORE_COUNT:0/, 'Filter true must suppress hook execution');
  assert.match(err.stdout || '', /HOOK_CALLED_COUNT:1/, 'Filter false must execute hook');
}
assert.strictEqual(filterTriggerThrew, true, 'Filtered event should exit with code 33');

// 6. assert unhookEvent removes the event handler and prevents hooks from executing
const childUnhookCode = `
  const exitHook = require('async-exit-hook');
  let hookRan = false;
  exitHook.hookEvent('tempEvent', 10);
  exitHook.unhookEvent('tempEvent');
  exitHook(() => {
    hookRan = true;
  });
  process.emit('tempEvent');
  console.log('AFTER_EMIT:hookRan=' + hookRan);
  process.exit(0);
`;

const outUnhook = execFileSync(process.execPath, ['-e', childUnhookCode], { encoding: 'utf8', timeout: 5000 });
assert.match(outUnhook, /AFTER_EMIT:hookRan=false/, 'Unhooked event must not trigger hook');

// 7. assert hookEvent supports asynchronous exit hooks before process termination
const childAsyncCode = `
  const exitHook = require('async-exit-hook');
  exitHook((done) => {
    setTimeout(() => {
      console.log('ASYNC_HOOK_COMPLETED');
      done();
    }, 50);
  });
  exitHook.hookEvent('asyncShutdown', 77);
  process.emit('asyncShutdown');
`;

let asyncThrew = false;
try {
  execFileSync(process.execPath, ['-e', childAsyncCode], { encoding: 'utf8', timeout: 5000 });
} catch (err) {
  asyncThrew = true;
  assert.strictEqual(err.status, 77, 'Async hook process should exit with code 77');
  assert.match(err.stdout || '', /ASYNC_HOOK_COMPLETED/, 'Async hook callback should complete before exit');
}
assert.strictEqual(asyncThrew, true, 'Async hook event should exit with code 77');

console.log('All async-exit-hook.hookEvent contract assertions passed.');