define-properties 1.2.1: define properties on object conditionally with predicates and support descriptor flags

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: define properties on object conditionally with predicates and support descriptor flags
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/define-properties@1.2.1
Demonstrate these symbols/APIs:
  - defineProperties
  - defineProperties.supportsDescriptors

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:bb7aab037f5ebca0ee636667f571c927cbb0bb070eb2b3a496a251f35ac007bf","contract":["defineProperties defines non-enumerable, writable, configurable properties on target object","defineProperties preserves existing properties when predicates are not provided or falsy","defineProperties overwrites existing properties when predicate is boolean true and value differs","defineProperties overwrites existing properties when predicate function returns truthy","defineProperties does not overwrite existing properties when predicate function returns falsy","defineProperties supports symbol keyed properties on target object","defineProperties.supportsDescriptors is a boolean indicating descriptor support"],"goal":"define properties on object conditionally with predicates and support descriptor flags","kind":"HOW","packages":["pkg:npm/define-properties@1.2.1"],"schemaVersion":1,"symbols":["defineProperties","defineProperties.supportsDescriptors"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/define-properties@1.2.1"],"schemaVersion":1,"subject":"pkg:npm/define-properties@1.2.1","symbols":["defineProperties","defineProperties.supportsDescriptors"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-define-properties",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-define-properties",
      "version": "1.0.0",
      "dependencies": {
        "define-properties": "1.2.1"
      }
    },
    "node_modules/define-data-property": {
      "version": "1.1.4",
      "resolved": "https://registry.npmjs.org/define-data-property/-/define-data-property-1.1.4.tgz",
      "integrity": "sha512-rBMvIzlpA8v6E+SJZoo++HAYqsLrkg7MSfIinMPFhmkorw7X+dOXVJQs+QT69zGkzMyfDnIMN2Wid1+NbL3T+A==",
      "license": "MIT",
      "dependencies": {
        "es-define-property": "^1.0.0",
        "es-errors": "^1.3.0",
        "gopd": "^1.0.1"
      },
      "engines": {
        "node": ">= 0.4"
      },
      "funding": {
        "url": "https://github.com/sponsors/ljharb"
      }
    },
    "node_modules/define-properties": {
      "version": "1.2.1",
      "resolved": "https://registry.npmjs.org/define-properties/-/define-properties-1.2.1.tgz",
      "integrity": "sha512-8QmQKqEASLd5nx0U1B1okLElbUuuttJ/AnYmRXbbbGDWh6uS208EjD4Xqq/I9wK7u0v6O08XhTWnt5XtEbR6Dg==",
      "license": "MIT",
      "dependencies": {
        "define-data-property": "^1.0.1",
        "has-property-descriptors": "^1.0.0",
        "object-keys": "^1.1.1"
      },
      "engines": {
        "node": ">= 0.4"
      },
      "funding": {
        "url": "https://github.com/sponsors/ljharb"
      }
    },
    "node_modules/es-define-property": {
      "version": "1.0.1",
      "resolved": "https://registry.npmjs.org/es-define-property/-/es-define-property-1.0.1.tgz",
      "integrity": "sha512-e3nRfgfUZ4rNGL232gUgX06QNyyez04KdjFrF+LTRoOXmrOgFKDg4BCdsjW8EnT69eqdYGmRpJwiPVYNrCaW3g==",
      "license": "MIT",
      "engines": {
        "node": ">= 0.4"
      }
    },
    "node_modules/es-errors": {
      "version": "1.3.0",
      "resolved": "https://registry.npmjs.org/es-errors/-/es-errors-1.3.0.tgz",
      "integrity": "sha512-Zf5H2Kxt2xjTvbJvP2ZWLEICxA6j+hAmMzIlypy4xcBg1vKVnx89Wy0GbS+kf5cwCVFFzdCFh2XSCFNULS6csw==",
      "license": "MIT",
      "engines": {
        "node": ">= 0.4"
      }
    },
    "node_modules/gopd": {
      "version": "1.2.0",
      "resolved": "https://registry.npmjs.org/gopd/-/gopd-1.2.0.tgz",
      "integrity": "sha512-ZUKRh6/kUFoAiTAtTYPZJ3hw9wNxx+BIBOijnlG9PnrJsCcSjs1wyyD6vJpaYtgnzDrKYRSqf3OO6Rfa93xsRg==",
      "license": "MIT",
      "engines": {
        "node": ">= 0.4"
      },
      "funding": {
        "url": "https://github.com/sponsors/ljharb"
      }
    },
    "node_modules/has-property-descriptors": {
      "version": "1.0.2",
      "resolved": "https://registry.npmjs.org/has-property-descriptors/-/has-property-descriptors-1.0.2.tgz",
      "integrity": "sha512-55JNKuIW+vq4Ke1BjOTjM2YctQIvCT7GFzHwmfZPGo5wnrgkid0YQtnAleFSqumZm4az3n2BS+erby5ipJdgrg==",
      "license": "MIT",
      "dependencies": {
        "es-define-property": "^1.0.0"
      },
      "funding": {
        "url": "https://github.com/sponsors/ljharb"
      }
    },
    "node_modules/object-keys": {
      "version": "1.1.1",
      "resolved": "https://registry.npmjs.org/object-keys/-/object-keys-1.1.1.tgz",
      "integrity": "sha512-NuAESUOUMrlIXOfHKzD6bpPu3tYt3xvjNdRIQ+FeT0lNb4K8WR70CaDxhuNguS2XG+GjkyMwOzsN5ZktImfhLA==",
      "license": "MIT",
      "engines": {
        "node": ">= 0.4"
      }
    }
  }
}

{
  "name": "sample-define-properties",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "dependencies": {
    "define-properties": "1.2.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "define properties on object conditionally with predicates and support descriptor flags",
  "kind": "HOW",
  "packages": [
    "pkg:npm/define-properties@1.2.1"
  ],
  "symbols": [
    "defineProperties",
    "defineProperties.supportsDescriptors"
  ]
}

import assert from 'node:assert/strict';
import defineProperties from 'define-properties';

// 1. defineProperties defines non-enumerable, writable, configurable properties on target object
{
  const target = {};
  defineProperties(target, {
    a: 1,
    b: 'hello',
  });

  assert.equal(target.a, 1);
  assert.equal(target.b, 'hello');
  assert.deepEqual(Object.keys(target), []);

  const descA = Object.getOwnPropertyDescriptor(target, 'a');
  assert.equal(descA.value, 1);
  assert.equal(descA.enumerable, false);
  assert.equal(descA.writable, true);
  assert.equal(descA.configurable, true);
}

// 2. defineProperties preserves existing properties when predicates are not provided or falsy
{
  const target = { a: 100, b: 200 };
  defineProperties(target, {
    a: 1,
    b: 2,
    c: 3,
  });

  assert.equal(target.a, 100);
  assert.equal(target.b, 200);
  assert.equal(target.c, 3);
}

// 3. defineProperties overwrites existing properties when predicate is boolean true and value differs
{
  const target = { a: 10, b: 20 };
  defineProperties(
    target,
    {
      a: 99,
      b: 20,
    },
    {
      a: true,
      b: true,
    }
  );

  assert.equal(target.a, 99);
  assert.equal(target.b, 20);
}

// 4. defineProperties overwrites existing properties when predicate function returns truthy
{
  const target = { a: 1, b: 2 };
  defineProperties(
    target,
    {
      a: 10,
      b: 20,
    },
    {
      a: () => true,
      b: () => 'truthy string',
    }
  );

  assert.equal(target.a, 10);
  assert.equal(target.b, 20);
}

// 5. defineProperties does not overwrite existing properties when predicate function returns falsy
{
  const target = { a: 1, b: 2 };
  let called = false;
  defineProperties(
    target,
    {
      a: 10,
      b: 20,
    },
    {
      a: () => {
        called = true;
        return false;
      },
      b: () => 0,
    }
  );

  assert.equal(called, true);
  assert.equal(target.a, 1);
  assert.equal(target.b, 2);
}

// 6. defineProperties supports symbol keyed properties on target object
{
  const sym = Symbol('foo');
  const target = {};
  defineProperties(target, {
    [sym]: 'bar',
  });

  assert.equal(target[sym], 'bar');
  const descSym = Object.getOwnPropertyDescriptor(target, sym);
  assert.equal(descSym.value, 'bar');
  assert.equal(descSym.enumerable, false);
}

// 7. defineProperties.supportsDescriptors is a boolean indicating descriptor support
{
  assert.equal(typeof defineProperties.supportsDescriptors, 'boolean');
  assert.equal(defineProperties.supportsDescriptors, true);
}