is-promise 4.0.0

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/is-promise@4.0.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/is-promise@4.0.0
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:sha256:167e9c79a785caf069ae2af0bfe7394adde2c000f991175344a803d691f8b2d6","constraints":{"executionContext":"node"},"contract":["isPromise returns true for native Promise instances and resolved Promises","isPromise returns true for custom thenable objects and thenable functions","isPromise returns false for primitives, null, undefined, plain objects, and plain functions"],"goal":"verify pkg:npm/is-promise@4.0.0","kind":"HOW","packages":["pkg:npm/is-promise@4.0.0"],"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/is-promise@4.0.0"],"schemaVersion":1,"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-is-promise",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-is-promise",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "is-promise": "4.0.0"
      }
    },
    "node_modules/is-promise": {
      "version": "4.0.0",
      "resolved": "https://registry.npmjs.org/is-promise/-/is-promise-4.0.0.tgz",
      "integrity": "sha512-hvpoI6korhJMnej285dSg6nu1+e6uxs7zG3BYAm5byqDsgJNWwxzM6z6iZiAgQR4TJ30JmBTOwqZUw3WlyH3AQ==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-is-promise",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification sample for is-promise",
  "main": "src/index.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "dependencies": {
    "is-promise": "4.0.0"
  },
  "license": "MIT-0"
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/is-promise@4.0.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/is-promise@4.0.0"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

const isPromise = require('is-promise');

function checkPromise(value) {
  return isPromise(value);
}

module.exports = {
  checkPromise
};

const assert = require('node:assert');
const isPromise = require('is-promise');
const { checkPromise } = require('../src/index.js');

// 1. Native Promise returns true
const nativePromise = new Promise((resolve) => resolve('done'));
assert.strictEqual(isPromise(nativePromise), true, 'native promise should return true');
assert.strictEqual(checkPromise(nativePromise), true, 'wrapper with native promise should return true');

// 2. Promise.resolve() returns true
const resolvedPromise = Promise.resolve(42);
assert.strictEqual(isPromise(resolvedPromise), true, 'Promise.resolve should return true');
assert.strictEqual(checkPromise(resolvedPromise), true, 'wrapper with Promise.resolve should return true');

// 3. Custom thenable object returns true
const thenableObj = {
  then(onFulfilled) {
    if (typeof onFulfilled === 'function') {
      onFulfilled('custom');
    }
  }
};
assert.strictEqual(isPromise(thenableObj), true, 'custom thenable object should return true');

// 4. Custom thenable function returns true
function thenableFunc() {}
thenableFunc.then = function() {};
assert.strictEqual(isPromise(thenableFunc), true, 'thenable function should return true');

// 5. Non-promise values return false
assert.strictEqual(isPromise(null), false, 'null should return false');
assert.strictEqual(isPromise(undefined), false, 'undefined should return false');
assert.strictEqual(isPromise(0), false, 'number 0 should return false');
assert.strictEqual(isPromise(123), false, 'number should return false');
assert.strictEqual(isPromise(''), false, 'empty string should return false');
assert.strictEqual(isPromise('hello'), false, 'string should return false');
assert.strictEqual(isPromise(true), false, 'boolean true should return false');
assert.strictEqual(isPromise(false), false, 'boolean false should return false');
assert.strictEqual(isPromise({}), false, 'plain object should return false');
assert.strictEqual(isPromise({ then: 'not a function' }), false, 'object with non-function then property should return false');
assert.strictEqual(isPromise(() => {}), false, 'plain function without then property should return false');
assert.strictEqual(isPromise([]), false, 'array should return false');

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