setprototypeof 1.2.0

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/setprototypeof@1.2.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/setprototypeof@1.2.0
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:ddb432f3825cceab8f017290e0d9bbf2b4c39783f8dcce4fde269a41057f2d8e","constraints":{"executionContext":"node"},"contract":["setPrototypeOf(obj, proto) mutates obj to inherit from proto and returns obj","inherited methods and properties from proto become accessible on obj","Object.getPrototypeOf(obj) returns proto after setPrototypeOf","setPrototypeOf(obj, null) sets object prototype to null with no Object.prototype inheritance"],"goal":"verify pkg:npm/setprototypeof@1.2.0","kind":"HOW","packages":["pkg:npm/setprototypeof@1.2.0"],"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/setprototypeof@1.2.0"],"schemaVersion":1,"verifierAdapter":"node-typescript@1"}

{
  "name": "csx-sample-setprototypeof",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "csx-sample-setprototypeof",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "setprototypeof": "1.2.0"
      }
    },
    "node_modules/setprototypeof": {
      "version": "1.2.0",
      "resolved": "https://registry.npmjs.org/setprototypeof/-/setprototypeof-1.2.0.tgz",
      "integrity": "sha512-E5LDX7Wrp85Kil5bhZv46j8jOeboKq5JMmYM3gVGdGH8xFpPWXUMsNrlODCrkoxMEeNi/XZIwuRvY4XNwYMJpw==",
      "license": "ISC"
    }
  }
}

{
  "name": "csx-sample-setprototypeof",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification for setprototypeof",
  "main": "test/contract.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "dependencies": {
    "setprototypeof": "1.2.0"
  },
  "license": "MIT-0"
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/setprototypeof@1.2.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/setprototypeof@1.2.0"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

const assert = require('assert');
const setPrototypeOf = require('setprototypeof');

// 1. Basic prototype inheritance
const proto = {
  greet() {
    return 'hello from proto';
  },
  value: 42
};

const obj = {
  ownProp: 'own'
};

const result = setPrototypeOf(obj, proto);

// setprototypeof returns the mutated target object
assert.strictEqual(result, obj, 'setPrototypeOf must return the target object');

// inherited properties and methods are accessible
assert.strictEqual(obj.greet(), 'hello from proto', 'inherited methods must be callable');
assert.strictEqual(obj.value, 42, 'inherited properties must be accessible');
assert.strictEqual(obj.ownProp, 'own', 'own properties must remain intact');

// Object.getPrototypeOf confirms prototype linkage
assert.strictEqual(Object.getPrototypeOf(obj), proto, 'Object.getPrototypeOf must match prototype');

// 2. Setting prototype to null creates a prototype-less dictionary
const nullProtoObj = { a: 1 };
setPrototypeOf(nullProtoObj, null);
assert.strictEqual(Object.getPrototypeOf(nullProtoObj), null, 'prototype should be null');
assert.strictEqual(nullProtoObj.toString, undefined, 'Object.prototype methods should not exist on null-prototype object');
assert.strictEqual(nullProtoObj.a, 1, 'own property should still be accessible');

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