neo-async 2.6.2: async.parallel

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.parallel 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.parallel
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:sha256:8de1e0381e68da3fd293f294cd964240dc9917302d01c332e7da498917060d7e","constraints":{"executionContext":"node"},"contract":["async.parallel executes an array of async tasks in parallel returning ordered results","async.parallel executes an object of named async tasks in parallel and returns results object with matching keys","async.parallel short-circuits immediately with error when any task fails","async.parallel handles empty collections immediately without error","async.parallel supports callback execution with synchronous and mixed tasks"],"goal":"verify async.parallel in pkg:npm/neo-async@2.6.2","kind":"HOW","packages":["pkg:npm/neo-async@2.6.2"],"schemaVersion":1,"symbols":["async.parallel"]},"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.parallel"],"verifierAdapter":"node-typescript@1"}

'use strict';

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

/**
 * Executes an array of asynchronous task functions in parallel.
 * @param {Array<Function>} tasks - Array of task functions: (callback) => void
 * @returns {Promise<Array<*>>} - Resolves with array of task results in original order
 */
function runParallelArray(tasks) {
  return new Promise((resolve, reject) => {
    async.parallel(tasks, (err, results) => {
      if (err) {
        return reject(err);
      }
      resolve(results);
    });
  });
}

/**
 * Executes a dictionary/object of named asynchronous task functions in parallel.
 * @param {Object.<string, Function>} tasks - Object mapping task names to task functions
 * @returns {Promise<Object.<string, *>>} - Resolves with object of task results mapped by key
 */
function runParallelObject(tasks) {
  return new Promise((resolve, reject) => {
    async.parallel(tasks, (err, results) => {
      if (err) {
        return reject(err);
      }
      resolve(results);
    });
  });
}

/**
 * Executes tasks in parallel with raw callback.
 * @param {Array<Function>|Object.<string, Function>} tasks
 * @param {Function} callback - (err, results) => void
 */
function executeParallel(tasks, callback) {
  return async.parallel(tasks, callback);
}

module.exports = {
  async,
  runParallelArray,
  runParallelObject,
  executeParallel,
};

{
  "name": "sample-neo-async-parallel",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-neo-async-parallel",
      "version": "1.0.0",
      "license": "MIT-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": "sample-neo-async-parallel",
  "version": "1.0.0",
  "description": "verify async.parallel in pkg:npm/neo-async@2.6.2",
  "main": "index.js",
  "license": "MIT-0",
  "dependencies": {
    "neo-async": "2.6.2"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify async.parallel in pkg:npm/neo-async@2.6.2",
  "kind": "HOW",
  "packages": [
    "pkg:npm/neo-async@2.6.2"
  ],
  "symbols": [
    "async.parallel"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

'use strict';

const assert = require('node:assert');
const {
  async,
  runParallelArray,
  runParallelObject,
  executeParallel,
} = require('../index.js');

async function runTests() {
  // Contract 1: async.parallel executes an array of async tasks in parallel returning ordered results
  {
    assert.strictEqual(typeof async.parallel, 'function', 'async.parallel must be a function');

    let task1Started = false;
    let task2Started = false;
    let task1Finished = false;
    let task2Finished = false;

    const tasks = [
      (callback) => {
        task1Started = true;
        setTimeout(() => {
          task1Finished = true;
          callback(null, 'first-result');
        }, 30);
      },
      (callback) => {
        task2Started = true;
        setTimeout(() => {
          task2Finished = true;
          callback(null, 'second-result');
        }, 10);
      },
    ];

    const results = await runParallelArray(tasks);

    assert.strictEqual(task1Started, true, 'Task 1 must have started');
    assert.strictEqual(task2Started, true, 'Task 2 must have started');
    assert.strictEqual(task1Finished, true, 'Task 1 must have finished');
    assert.strictEqual(task2Finished, true, 'Task 2 must have finished');
    assert.deepStrictEqual(results, ['first-result', 'second-result'], 'Results must maintain input array order regardless of completion time');
  }

  // Contract 2: async.parallel executes an object of named async tasks in parallel and returns results object with matching keys
  {
    const tasks = {
      taskA: (callback) => {
        setTimeout(() => callback(null, 100), 20);
      },
      taskB: (callback) => {
        setTimeout(() => callback(null, 'hello'), 10);
      },
      taskC: (callback) => {
        callback(null, { nested: true });
      },
    };

    const results = await runParallelObject(tasks);

    assert.deepStrictEqual(
      results,
      {
        taskA: 100,
        taskB: 'hello',
        taskC: { nested: true },
      },
      'Results object must match task keys'
    );
  }

  // Contract 3: async.parallel short-circuits immediately with error when any task fails
  {
    let taskAfterErrorCompleted = false;

    const tasks = [
      (callback) => {
        setTimeout(() => {
          callback(new Error('Task 1 failed'));
        }, 10);
      },
      (callback) => {
        setTimeout(() => {
          taskAfterErrorCompleted = true;
          callback(null, 'Task 2 success');
        }, 100);
      },
    ];

    await assert.rejects(
      async () => {
        await runParallelArray(tasks);
      },
      (err) => {
        assert.strictEqual(err.message, 'Task 1 failed');
        return true;
      },
      'Must reject with error from the failed task'
    );
  }

  // Contract 4: async.parallel handles empty collections immediately without error
  {
    const emptyArrayResult = await runParallelArray([]);
    assert.deepStrictEqual(emptyArrayResult, [], 'Empty array tasks must resolve with empty array');

    const emptyObjectResult = await runParallelObject({});
    assert.deepStrictEqual(emptyObjectResult, {}, 'Empty object tasks must resolve with empty object');
  }

  // Contract 5: async.parallel supports callback execution with synchronous and mixed tasks
  {
    await new Promise((resolve, reject) => {
      executeParallel(
        [
          (cb) => cb(null, 1),
          (cb) => cb(null, 2),
          (cb) => process.nextTick(() => cb(null, 3)),
        ],
        (err, results) => {
          if (err) return reject(err);
          try {
            assert.deepStrictEqual(results, [1, 2, 3]);
            resolve();
          } catch (e) {
            reject(e);
          }
        }
      );
    });
  }

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

runTests().catch((err) => {
  console.error('Contract tests failed:', err);
  process.exit(1);
});