neo-async 2.6.2: async.each

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.each in pkg:npm/neo-async@2.6.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/neo-async@2.6.2
Demonstrate these symbols/APIs:
  - async.each

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:sha256:3ee13f5fc7aa5dc029328ba0a3164cba98b8196f9f0f7b3c7ae9025803f51a13","contract":["async.each(coll, iteratee, callback) iterates over array items in parallel and completes with null error","async.each(coll, iteratee, callback) short-circuits and forwards the first error when an iteratee fails","async.each(coll, iteratee, callback) completes immediately with null for empty array or collection","async.each(coll, iteratee, callback) iterates over key-value entries when given an object dictionary","async.each(coll, iteratee, callback) supports synchronous iteratee completion without throwing","async.forEach is an exact alias of async.each"],"goal":"verify async.each in pkg:npm/neo-async@2.6.2","kind":"HOW","packages":["pkg:npm/neo-async@2.6.2"],"schemaVersion":1,"symbols":["async.each"]},"contractCommand":["node","test/contract.cjs"],"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/neo-async@2.6.2"],"schemaVersion":1,"subject":"pkg:npm/neo-async@2.6.2","symbols":["async.each"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-neo-async",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-neo-async",
      "version": "1.0.0",
      "dependencies": {
        "neo-async": "2.6.2"
      }
    },
    "node_modules/neo-async": {
      "version": "2.6.2",
      "resolved": "https://registry.npmjs.org/neo-async/-/neo-async-2.6.2.tgz",
      "integrity": "sha512-Yd3UES5mWCSqR+qNT93S3UoYUkqAZ9lLg8a7g9rimsWmYGK8cVToA4/sF3RrshdyV3sAGMXVUmpMYOw+dLpOuw==",
      "license": "MIT"
    }
  }
}

{
  "name": "verify-neo-async-each",
  "version": "1.0.0",
  "private": true,
  "description": "verify async.each in pkg:npm/neo-async@2.6.2",
  "main": "src/index.js",
  "scripts": {
    "test": "node test/contract.cjs"
  },
  "dependencies": {
    "neo-async": "2.6.2"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify async.each in pkg:npm/neo-async@2.6.2",
  "kind": "HOW",
  "packages": [
    "pkg:npm/neo-async@2.6.2"
  ],
  "symbols": [
    "async.each"
  ]
}

const async = require('neo-async');

/**
 * Applies an asynchronous iteratee function to each item in coll in parallel.
 *
 * @param {Array|Object} coll - A collection to iterate over.
 * @param {Function} iteratee - An async function to apply to each item in coll (item, callback).
 * @param {Function} callback - A callback which is called when all iteratee functions have finished, or an error occurs.
 */
function each(coll, iteratee, callback) {
  return async.each(coll, iteratee, callback);
}

/**
 * Promise-wrapped version of async.each.
 *
 * @param {Array|Object} coll - A collection to iterate over.
 * @param {Function} iteratee - An async function (item, callback) or async function returning a promise.
 * @returns {Promise<void>} Resolves when all items have been processed or rejects on error.
 */
function eachPromise(coll, iteratee) {
  return new Promise((resolve, reject) => {
    async.each(coll, (item, next) => {
      try {
        const res = iteratee(item, next);
        if (res && typeof res.then === 'function') {
          res.then(() => next()).catch((err) => next(err));
        }
      } catch (err) {
        next(err);
      }
    }, (err) => {
      if (err) {
        return reject(err);
      }
      resolve();
    });
  });
}

module.exports = {
  async,
  each,
  eachPromise,
};

const assert = require('node:assert/strict');
const async = require('neo-async');
const { each, eachPromise } = require('../src/index.js');

async function runContractTests() {
  // 1. async.each(coll, iteratee, callback) iterates over array items in parallel and completes with null error
  await new Promise((resolve, reject) => {
    const input = [1, 2, 3, 4];
    const results = [];

    async.each(input, (item, next) => {
      setTimeout(() => {
        results.push(item * 10);
        next();
      }, 20);
    }, (err) => {
      try {
        assert.strictEqual(err, null, 'Error must be null on successful execution');
        assert.strictEqual(results.length, 4, 'All 4 items must be processed');
        assert.deepStrictEqual(results.sort((a, b) => a - b), [10, 20, 30, 40]);
        resolve();
      } catch (e) {
        reject(e);
      }
    });
  });

  // 2. async.each(coll, iteratee, callback) short-circuits and forwards the first error when an iteratee fails
  await new Promise((resolve, reject) => {
    const input = [10, 20, 30, 40];
    let processedCount = 0;

    async.each(input, (item, next) => {
      if (item === 20) {
        return next(new Error('simulated error at item 20'));
      }
      processedCount++;
      next();
    }, (err) => {
      try {
        assert.ok(err instanceof Error, 'Expected err to be an instance of Error');
        assert.strictEqual(err.message, 'simulated error at item 20');
        resolve();
      } catch (e) {
        reject(e);
      }
    });
  });

  // 3. async.each(coll, iteratee, callback) completes immediately with null for empty array or collection
  await new Promise((resolve, reject) => {
    let iterateeCalled = false;

    async.each([], (item, next) => {
      iterateeCalled = true;
      next();
    }, (err) => {
      try {
        assert.strictEqual(err, null, 'Callback error must be null');
        assert.strictEqual(iterateeCalled, false, 'Iteratee must not be called for empty collection');
        resolve();
      } catch (e) {
        reject(e);
      }
    });
  });

  // 4. async.each(coll, iteratee, callback) iterates over key-value entries when given an object dictionary
  await new Promise((resolve, reject) => {
    const obj = { alpha: 'A', beta: 'B', gamma: 'C' };
    const collectedValues = [];

    async.each(obj, (val, next) => {
      collectedValues.push(val);
      next();
    }, (err) => {
      try {
        assert.strictEqual(err, null, 'Error must be null');
        assert.deepStrictEqual(collectedValues.sort(), ['A', 'B', 'C']);
        resolve();
      } catch (e) {
        reject(e);
      }
    });
  });

  // 5. async.each(coll, iteratee, callback) supports synchronous iteratee completion without throwing
  await new Promise((resolve, reject) => {
    const numbers = [5, 10, 15];
    const squared = [];

    each(numbers, (num, next) => {
      squared.push(num * num);
      next();
    }, (err) => {
      try {
        assert.strictEqual(err, null);
        assert.deepStrictEqual(squared, [25, 100, 225]);
        resolve();
      } catch (e) {
        reject(e);
      }
    });
  });

  // 6. async.forEach is an exact alias of async.each
  assert.strictEqual(async.forEach, async.each, 'async.forEach must be strictly equal to async.each');

  console.log('All contract tests passed.');
}

runContractTests().catch((err) => {
  console.error('Contract test failure:', err);
  process.exit(1);
});