tiny-typed-emitter 2.1.0: TypedEmitter

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 tiny-typed-emitter.TypedEmitter in pkg:npm/tiny-typed-emitter@2.1.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/tiny-typed-emitter@2.1.0
Demonstrate these symbols/APIs:
  - tiny-typed-emitter.TypedEmitter

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:sha256:863e17890f90c2ec021fea9c7de2b43a5fd15ae0cdb56f223afa3f7d2ba9fa3c","contract":["tiny-typed-emitter exports TypedEmitter class","TypedEmitter instances register event listeners via on and addListener","TypedEmitter emit invokes listeners with provided arguments and returns true when listeners exist","TypedEmitter once registers a single-execution listener that unregisters after firing","TypedEmitter prependListener and prependOnceListener add listeners to the beginning of the listener array","TypedEmitter off and removeListener unregister specific listeners","TypedEmitter removeAllListeners clears all listeners for an event or all events","TypedEmitter listenerCount, listeners, and eventNames accurately reflect registered event state","TypedEmitter getMaxListeners and setMaxListeners manage listener capacity limits"],"goal":"verify tiny-typed-emitter.TypedEmitter in pkg:npm/tiny-typed-emitter@2.1.0","kind":"HOW","packages":["pkg:npm/tiny-typed-emitter@2.1.0"],"schemaVersion":1,"symbols":["tiny-typed-emitter.TypedEmitter"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/tiny-typed-emitter@2.1.0"],"schemaVersion":1,"subject":"pkg:npm/tiny-typed-emitter@2.1.0","symbols":["tiny-typed-emitter.TypedEmitter"],"verifierAdapter":"node-typescript@1"}

import { TypedEmitter } from 'tiny-typed-emitter';

export { TypedEmitter };

/**
 * Creates a new instance of TypedEmitter.
 *
 * @returns {TypedEmitter} A fresh event emitter instance.
 */
export function createEmitter() {
  return new TypedEmitter();
}

export default TypedEmitter;

{
  "name": "sample-tiny-typed-emitter",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-tiny-typed-emitter",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "tiny-typed-emitter": "2.1.0"
      }
    },
    "node_modules/tiny-typed-emitter": {
      "version": "2.1.0",
      "resolved": "https://registry.npmjs.org/tiny-typed-emitter/-/tiny-typed-emitter-2.1.0.tgz",
      "integrity": "sha512-qVtvMxeXbVej0cQWKqVSSAHmKZEHAvxdF8HEUBFWts8h+xEo5m/lEiPakuyZ3BnCBjOD8i24kzNOiOLLgsSxhA==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-tiny-typed-emitter",
  "version": "1.0.0",
  "type": "module",
  "main": "index.mjs",
  "license": "MIT-0",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "tiny-typed-emitter": "2.1.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify tiny-typed-emitter.TypedEmitter in pkg:npm/tiny-typed-emitter@2.1.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/tiny-typed-emitter@2.1.0"
  ],
  "symbols": [
    "tiny-typed-emitter.TypedEmitter"
  ]
}

import assert from 'node:assert/strict';
import { TypedEmitter } from 'tiny-typed-emitter';
import { createEmitter } from '../index.mjs';

// 1. tiny-typed-emitter exports TypedEmitter class
assert.equal(typeof TypedEmitter, 'function', 'TypedEmitter should be exported as a constructor/class');
assert.equal(typeof createEmitter, 'function', 'createEmitter helper should be a function');

const emitter = new TypedEmitter();
assert.ok(emitter instanceof TypedEmitter, 'emitter should be an instance of TypedEmitter');

const created = createEmitter();
assert.ok(created instanceof TypedEmitter, 'createEmitter should return a TypedEmitter instance');

// 2. TypedEmitter instances register event listeners via on and addListener
let countA = 0;
const listenerA = () => { countA++; };
const returnedOn = emitter.on('eventA', listenerA);
assert.equal(returnedOn, emitter, 'on() should return this for chaining');

let countB = 0;
const listenerB = () => { countB++; };
const returnedAdd = emitter.addListener('eventB', listenerB);
assert.equal(returnedAdd, emitter, 'addListener() should return this for chaining');

// 3. TypedEmitter emit invokes listeners with provided arguments and returns true when listeners exist
let receivedPayload = null;
emitter.on('data', (val1, val2) => {
  receivedPayload = [val1, val2];
});

const emittedData = emitter.emit('data', 'hello', 42);
assert.equal(emittedData, true, 'emit() should return true when listeners exist');
assert.deepEqual(receivedPayload, ['hello', 42], 'listener should receive emitted arguments');

const emittedNonExistent = emitter.emit('unknownEvent');
assert.equal(emittedNonExistent, false, 'emit() should return false when no listeners exist');

// 4. TypedEmitter once registers a single-execution listener that unregisters after firing
let onceCount = 0;
emitter.once('single', (val) => {
  onceCount += val;
});

assert.equal(emitter.listenerCount('single'), 1, 'listenerCount should be 1 before firing');
emitter.emit('single', 5);
assert.equal(onceCount, 5, 'once listener should be executed');
assert.equal(emitter.listenerCount('single'), 0, 'listenerCount should be 0 after firing');
emitter.emit('single', 5);
assert.equal(onceCount, 5, 'once listener should not fire a second time');

// 5. TypedEmitter prependListener and prependOnceListener add listeners to the beginning of the listener array
const order = [];
emitter.on('orderTest', () => { order.push('second'); });
emitter.prependListener('orderTest', () => { order.push('first'); });
emitter.emit('orderTest');
assert.deepEqual(order, ['first', 'second'], 'prepended listener should fire first');

const onceOrder = [];
emitter.on('prependOnceTest', () => { onceOrder.push('normal'); });
emitter.prependOnceListener('prependOnceTest', () => { onceOrder.push('prepended-once'); });
emitter.emit('prependOnceTest');
assert.deepEqual(onceOrder, ['prepended-once', 'normal'], 'prepended once listener should fire first');
emitter.emit('prependOnceTest');
assert.deepEqual(onceOrder, ['prepended-once', 'normal', 'normal'], 'prepended once listener should only fire once');

// 6. TypedEmitter off and removeListener unregister specific listeners
let removeTestCount = 0;
const removableListener = () => { removeTestCount++; };
emitter.on('removable', removableListener);
emitter.emit('removable');
assert.equal(removeTestCount, 1);

const returnedOff = emitter.off('removable', removableListener);
assert.equal(returnedOff, emitter, 'off() should return this for chaining');
emitter.emit('removable');
assert.equal(removeTestCount, 1, 'listener should not fire after off()');

emitter.on('removable2', removableListener);
emitter.removeListener('removable2', removableListener);
assert.equal(emitter.listenerCount('removable2'), 0, 'listenerCount should be 0 after removeListener');

// 7. TypedEmitter removeAllListeners clears all listeners for an event or all events
emitter.on('multi', () => {});
emitter.on('multi', () => {});
assert.equal(emitter.listenerCount('multi'), 2);
emitter.removeAllListeners('multi');
assert.equal(emitter.listenerCount('multi'), 0, 'removeAllListeners(event) should remove listeners for event');

emitter.on('ev1', () => {});
emitter.on('ev2', () => {});
emitter.removeAllListeners();
assert.equal(emitter.eventNames().length, 0, 'removeAllListeners() should clear all events');

// 8. TypedEmitter listenerCount, listeners, and eventNames accurately reflect registered event state
const fn1 = () => {};
const fn2 = () => {};
emitter.on('inspect', fn1);
emitter.on('inspect', fn2);

assert.equal(emitter.listenerCount('inspect'), 2);
assert.deepEqual(emitter.listeners('inspect'), [fn1, fn2]);
assert.ok(emitter.eventNames().includes('inspect'));

// 9. TypedEmitter getMaxListeners and setMaxListeners manage listener capacity limits
const currentMax = emitter.getMaxListeners();
assert.equal(typeof currentMax, 'number');
emitter.setMaxListeners(25);
assert.equal(emitter.getMaxListeners(), 25);
assert.equal(typeof TypedEmitter.defaultMaxListeners, 'number');

console.log('All tiny-typed-emitter.TypedEmitter contract tests passed.');