object-assign 4.1.1

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 pkg:npm/object-assign@4.1.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/object-assign@4.1.1
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:b9503373a7bbaf4f6c818b5db18f093bd918d616e9031d49c5293c60c7a36709","constraints":{"executionContext":"node"},"contract":["objectAssign mutates and returns the target object","objectAssign merges own enumerable properties from multiple source objects with later sources overriding earlier ones","objectAssign ignores null and undefined sources without throwing","objectAssign throws TypeError when target is null or undefined","objectAssign supports Symbol properties from source objects","objectAssign treats string primitives as objects with indexed enumerable properties while ignoring other primitives"],"goal":"verify pkg:npm/object-assign@4.1.1","kind":"HOW","packages":["pkg:npm/object-assign@4.1.1"],"schemaVersion":1},"contractCommand":["node","test/contract.js"],"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/object-assign@4.1.1"],"schemaVersion":1,"subject":"pkg:npm/object-assign@4.1.1","verifierAdapter":"node-typescript@1"}

{
  "name": "sample-object-assign",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-object-assign",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "object-assign": "4.1.1"
      }
    },
    "node_modules/object-assign": {
      "version": "4.1.1",
      "resolved": "https://registry.npmjs.org/object-assign/-/object-assign-4.1.1.tgz",
      "integrity": "sha512-rJgTQnkUnH1sFw8yT6VSU3zD3sWmu6sZhIseY8VX+GRu3P6F7Fu+JNDoXfklElbLJSnc3FUQHVe4cU5hj+BcUg==",
      "license": "MIT",
      "engines": {
        "node": ">=0.10.0"
      }
    }
  }
}

{
  "name": "sample-object-assign",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification sample for object-assign",
  "main": "src/index.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "dependencies": {
    "object-assign": "4.1.1"
  },
  "license": "MIT-0"
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/object-assign@4.1.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/object-assign@4.1.1"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

'use strict';

const objectAssign = require('object-assign');

/**
 * Merges source objects into target object using object-assign.
 * @param {object} target
 * @param {...object} sources
 * @returns {object}
 */
function mergeObjects(target, ...sources) {
  return objectAssign(target, ...sources);
}

module.exports = {
  objectAssign,
  mergeObjects
};

'use strict';

const assert = require('assert');
const objectAssign = require('object-assign');
const { mergeObjects } = require('../src/index.js');

// 1. objectAssign mutates and returns the target object
{
  const target = { a: 1 };
  const result = objectAssign(target, { b: 2 });
  assert.strictEqual(result, target);
  assert.strictEqual(target.a, 1);
  assert.strictEqual(target.b, 2);

  const target2 = { x: 10 };
  const result2 = mergeObjects(target2, { y: 20 });
  assert.strictEqual(result2, target2);
  assert.strictEqual(target2.x, 10);
  assert.strictEqual(target2.y, 20);
}

// 2. objectAssign merges own enumerable properties from multiple source objects with later sources overriding earlier ones
{
  const target = { a: 1, b: 1 };
  const src1 = { b: 2, c: 2 };
  const src2 = { c: 3, d: 4 };
  const result = objectAssign(target, src1, src2);

  assert.deepStrictEqual(result, { a: 1, b: 2, c: 3, d: 4 });
  assert.strictEqual(target.a, 1);
  assert.strictEqual(target.b, 2);
  assert.strictEqual(target.c, 3);
  assert.strictEqual(target.d, 4);
}

// 3. objectAssign ignores null and undefined sources without throwing
{
  const target = { a: 1 };
  const result = objectAssign(target, null, undefined, { b: 2 }, undefined, null);
  assert.strictEqual(result, target);
  assert.deepStrictEqual(result, { a: 1, b: 2 });
}

// 4. objectAssign throws TypeError when target is null or undefined
{
  assert.throws(
    () => {
      objectAssign(null, { a: 1 });
    },
    {
      name: 'TypeError'
    }
  );

  assert.throws(
    () => {
      objectAssign(undefined, { a: 1 });
    },
    {
      name: 'TypeError'
    }
  );
}

// 5. objectAssign supports Symbol properties from source objects
{
  const symA = Symbol('symA');
  const symB = Symbol('symB');
  const target = {};
  const src = { [symA]: 'valueA', [symB]: 'valueB', normal: 'regular' };

  const result = objectAssign(target, src);
  assert.strictEqual(result[symA], 'valueA');
  assert.strictEqual(result[symB], 'valueB');
  assert.strictEqual(result.normal, 'regular');
}

// 6. objectAssign treats string primitives as objects with indexed enumerable properties while ignoring other primitives
{
  const target = {};
  const result = objectAssign(target, 42, true, 'foo', Symbol('test'));
  assert.strictEqual(result['0'], 'f');
  assert.strictEqual(result['1'], 'o');
  assert.strictEqual(result['2'], 'o');
}

console.log('Contract tests passed successfully.');