jest-worker 29.7.0: Worker

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 jest-worker.Worker in pkg:npm/jest-worker@29.7.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/jest-worker@29.7.0
Demonstrate these symbols/APIs:
  - jest-worker.Worker

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:sha256:8ff3249e46f29f99affd64e27f28c81baf9db3f64a5c21d446663b3ac405d0fc","contract":["Worker constructor throws when workerPath is relative","Worker supports instantiation with a file URL","Worker executes exposed methods in parallel worker threads and returns resolved results","Worker propagates synchronous exceptions and asynchronous rejections","Worker exposes stdout and stderr readable streams via getStdout and getStderr","Worker routes tasks to consistent workers using computeWorkerKey","Worker supports custom task queue implementations like FifoQueue and PriorityQueue","Worker start initializes workers and end terminates the farm rejecting subsequent calls"],"goal":"verify jest-worker.Worker in pkg:npm/jest-worker@29.7.0","kind":"HOW","packages":["pkg:npm/jest-worker@29.7.0"],"schemaVersion":1,"symbols":["jest-worker.Worker"]},"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/jest-worker@29.7.0"],"schemaVersion":1,"subject":"pkg:npm/jest-worker@29.7.0","symbols":["jest-worker.Worker"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-jest-worker-worker",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-jest-worker-worker",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "jest-worker": "29.7.0"
      }
    },
    "node_modules/@jest/schemas": {
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      "resolved": "https://registry.npmjs.org/@jest/schemas/-/schemas-29.6.3.tgz",
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      "license": "MIT",
      "dependencies": {
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      },
      "engines": {
        "node": "^14.15.0 || ^16.10.0 || >=18.0.0"
      }
    },
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      "resolved": "https://registry.npmjs.org/@jest/types/-/types-29.6.3.tgz",
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      "dependencies": {
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        "@types/istanbul-reports": "^3.0.0",
        "@types/node": "*",
        "@types/yargs": "^17.0.8",
        "chalk": "^4.0.0"
      },
      "engines": {
        "node": "^14.15.0 || ^16.10.0 || >=18.0.0"
      }
    },
    "node_modules/@sinclair/typebox": {
      "version": "0.27.12",
      "resolved": "https://registry.npmjs.org/@sinclair/typebox/-/typebox-0.27.12.tgz",
      "integrity": "sha512-hhyNJ+nbR6ZR7pToHvllEFun9TL0sbL+tk/ON75lo+Xas054uez98qRbsuNt7MBCyZKK4+8Yli/OAGZhmfBZ/g==",
      "license": "MIT"
    },
    "node_modules/@types/istanbul-lib-coverage": {
      "version": "2.0.6",
      "resolved": "https://registry.npmjs.org/@types/istanbul-lib-coverage/-/istanbul-lib-coverage-2.0.6.tgz",
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      "license": "MIT"
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      "resolved": "https://registry.npmjs.org/@types/node/-/node-26.4.1.tgz",
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      "funding": {
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      "resolved": "https://registry.npmjs.org/chalk/-/chalk-4.1.2.tgz",
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      },
      "engines": {
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      "funding": {
        "url": "https://github.com/chalk/chalk?sponsor=1"
      }
    },
    "node_modules/chalk/node_modules/supports-color": {
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      "license": "MIT",
      "dependencies": {
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    "node_modules/ci-info": {
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      "resolved": "https://registry.npmjs.org/ci-info/-/ci-info-3.9.0.tgz",
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      "license": "MIT",
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      "dependencies": {
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      },
      "engines": {
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    },
    "node_modules/color-name": {
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      "resolved": "https://registry.npmjs.org/color-name/-/color-name-1.1.4.tgz",
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      "license": "MIT"
    },
    "node_modules/graceful-fs": {
      "version": "4.2.11",
      "resolved": "https://registry.npmjs.org/graceful-fs/-/graceful-fs-4.2.11.tgz",
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    },
    "node_modules/has-flag": {
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      "resolved": "https://registry.npmjs.org/has-flag/-/has-flag-4.0.0.tgz",
      "integrity": "sha512-EykJT/Q1KjTWctppgIAgfSO0tKVuZUjhgMr17kqTumMl6Afv3EISleU7qZUzoXDFTAHTDC4NOoG/ZxU3EvlMPQ==",
      "license": "MIT",
      "engines": {
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    },
    "node_modules/jest-util": {
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      "resolved": "https://registry.npmjs.org/jest-util/-/jest-util-29.7.0.tgz",
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      "dependencies": {
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        "ci-info": "^3.2.0",
        "graceful-fs": "^4.2.9",
        "picomatch": "^2.2.3"
      },
      "engines": {
        "node": "^14.15.0 || ^16.10.0 || >=18.0.0"
      }
    },
    "node_modules/jest-worker": {
      "version": "29.7.0",
      "resolved": "https://registry.npmjs.org/jest-worker/-/jest-worker-29.7.0.tgz",
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      "license": "MIT"
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  }
}

{
  "name": "sample-jest-worker-worker",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "license": "MIT-0",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "jest-worker": "29.7.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify jest-worker.Worker in pkg:npm/jest-worker@29.7.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/jest-worker@29.7.0"
  ],
  "symbols": [
    "jest-worker.Worker"
  ]
}

import path from 'node:path';
import { fileURLToPath } from 'node:url';
import { Worker, FifoQueue, PriorityQueue, messageParent } from 'jest-worker';

export { Worker, FifoQueue, PriorityQueue, messageParent };

const __dirname = path.dirname(fileURLToPath(import.meta.url));
export const WORKER_TASK_PATH = path.join(__dirname, 'workerTask.cjs');

export function createWorker(options = {}) {
  return new Worker(WORKER_TASK_PATH, {
    numWorkers: 2,
    enableWorkerThreads: true,
    exposedMethods: [
      'add',
      'multiply',
      'concat',
      'reverseString',
      'throwError',
      'rejectPromise',
      'writeStdout',
      'writeStderr',
      'getWorkerInfo',
    ],
    ...options,
  });
}

'use strict';

function add(a, b) {
  return a + b;
}

function multiply(a, b) {
  return a * b;
}

function concat(...parts) {
  return parts.join('');
}

function reverseString(str) {
  return str.split('').reverse().join('');
}

function throwError(message) {
  throw new Error(message);
}

function rejectPromise(message) {
  return Promise.reject(new Error(message));
}

function writeStdout(msg) {
  process.stdout.write(msg + '\n');
  return true;
}

function writeStderr(msg) {
  process.stderr.write(msg + '\n');
  return true;
}

function getWorkerInfo() {
  const wt = require('node:worker_threads');
  return {
    isMainThread: wt.isMainThread,
    threadId: wt.threadId,
    pid: process.pid,
  };
}

module.exports = {
  add,
  multiply,
  concat,
  reverseString,
  throwError,
  rejectPromise,
  writeStdout,
  writeStderr,
  getWorkerInfo,
};

import assert from 'node:assert';
import { pathToFileURL } from 'node:url';
import {
  Worker,
  FifoQueue,
  PriorityQueue,
  createWorker,
  WORKER_TASK_PATH,
} from '../src/index.mjs';

// 1. Worker constructor throws when workerPath is relative
{
  assert.throws(
    () => {
      new Worker('./src/workerTask.cjs');
    },
    {
      name: 'Error',
      message: "'workerPath' must be absolute, got './src/workerTask.cjs'",
    }
  );
}

// 2. Worker supports instantiation with a file URL
{
  const workerUrl = pathToFileURL(WORKER_TASK_PATH);
  const farm = new Worker(workerUrl, {
    numWorkers: 2,
    enableWorkerThreads: true,
    exposedMethods: ['add'],
  });
  const sum = await farm.add(15, 27);
  assert.strictEqual(sum, 42);
  await farm.end();
}

// 3. Worker executes exposed methods in parallel worker threads and returns resolved results
{
  const farm = createWorker({ numWorkers: 2 });
  const [addRes, mulRes, concatRes, revRes] = await Promise.all([
    farm.add(10, 32),
    farm.multiply(6, 7),
    farm.concat('Code', 'Sample', 'X'),
    farm.reverseString('Antigravity'),
  ]);
  assert.strictEqual(addRes, 42);
  assert.strictEqual(mulRes, 42);
  assert.strictEqual(concatRes, 'CodeSampleX');
  assert.strictEqual(revRes, 'ytivargitnA');

  const info = await farm.getWorkerInfo();
  assert.strictEqual(info.isMainThread, false);
  assert.strictEqual(typeof info.threadId, 'number');

  await farm.end();
}

// 4. Worker propagates synchronous exceptions and asynchronous rejections
{
  const farm = createWorker({ numWorkers: 1 });
  await assert.rejects(
    async () => {
      await farm.throwError('sync worker failure');
    },
    {
      name: 'Error',
      message: 'sync worker failure',
    }
  );
  await assert.rejects(
    async () => {
      await farm.rejectPromise('async worker rejection');
    },
    {
      name: 'Error',
      message: 'async worker rejection',
    }
  );
  await farm.end();
}

// 5. Worker exposes stdout and stderr readable streams via getStdout and getStderr
{
  const farm = createWorker({ numWorkers: 1 });
  const stdout = farm.getStdout();
  const stderr = farm.getStderr();

  assert.strictEqual(typeof stdout.pipe, 'function');
  assert.strictEqual(typeof stdout.on, 'function');
  assert.strictEqual(typeof stderr.pipe, 'function');
  assert.strictEqual(typeof stderr.on, 'function');

  await farm.end();
}

// 6. Worker routes tasks to consistent workers using computeWorkerKey
{
  const farm = createWorker({
    numWorkers: 2,
    computeWorkerKey: (method, key) => key,
  });

  const [r1, r2, r3] = await Promise.all([
    farm.getWorkerInfo('partition-key-1'),
    farm.getWorkerInfo('partition-key-1'),
    farm.getWorkerInfo('partition-key-1'),
  ]);
  assert.strictEqual(r1.threadId, r2.threadId);
  assert.strictEqual(r2.threadId, r3.threadId);

  await farm.end();
}

// 7. Worker supports custom task queue implementations like FifoQueue and PriorityQueue
{
  const fifoFarm = createWorker({
    numWorkers: 1,
    taskQueue: new FifoQueue(),
  });
  const fifoRes = await fifoFarm.add(5, 5);
  assert.strictEqual(fifoRes, 10);
  await fifoFarm.end();

  const pqFarm = createWorker({
    numWorkers: 1,
    taskQueue: new PriorityQueue((method, a) => (typeof a === 'number' ? a : 0)),
  });
  const pqRes = await pqFarm.multiply(4, 5);
  assert.strictEqual(pqRes, 20);
  await pqFarm.end();
}

// 8. Worker start initializes workers and end terminates the farm rejecting subsequent calls
{
  const farm = createWorker({ numWorkers: 1 });
  await farm.start();
  const preCheck = await farm.add(1, 1);
  assert.strictEqual(preCheck, 2);

  const endResult = await farm.end();
  assert.strictEqual(typeof endResult, 'object');

  await assert.rejects(
    async () => {
      await farm.add(1, 2);
    },
    {
      name: 'Error',
      message: 'Farm is ended, no more calls can be done to it',
    }
  );
}

console.log('All contract assertions passed.');