punycode 2.3.1: toASCII

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 punycode.toASCII in pkg:npm/punycode@2.3.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/punycode@2.3.1
Demonstrate these symbols/APIs:
  - punycode.toASCII
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:f6f0ff57b847ef9c43a905e236ef6d3db7966ee75577056246aaf9761e8ea766","constraints":{"executionContext":"node"},"contract":["punycode.toASCII converts internationalized domain names with Unicode characters to Punycode ASCII encoding","punycode.toASCII leaves ASCII-only domain names unchanged"],"goal":"verify punycode.toASCII in pkg:npm/punycode@2.3.1","kind":"HOW","packages":["pkg:npm/punycode@2.3.1"],"schemaVersion":1,"symbols":["punycode.toASCII"]},"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/punycode@2.3.1"],"schemaVersion":1,"symbols":["punycode.toASCII"],"verifierAdapter":"node-typescript@1"}

const punycode = require('punycode/');

/**
 * Converts a domain name with Unicode characters to its Punycode ASCII representation.
 *
 * @param {string} domain - The domain name to convert.
 * @returns {string} The ASCII-compatible encoded domain name.
 */
function toASCII(domain) {
  return punycode.toASCII(domain);
}

module.exports = {
  toASCII,
  punycode
};

{
  "name": "punycode-toascii-verification",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "punycode-toascii-verification",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "punycode": "2.3.1"
      }
    },
    "node_modules/punycode": {
      "version": "2.3.1",
      "resolved": "https://registry.npmjs.org/punycode/-/punycode-2.3.1.tgz",
      "integrity": "sha512-vYt7UD1U9Wg6138shLtLOvdAu+8DsC/ilFtEVHcH+wydcSpNE20AfSOduf6MkRFahL5FY7X1oU7nKVZFtfq8Fg==",
      "license": "MIT",
      "engines": {
        "node": ">=6"
      }
    }
  }
}

{
  "name": "punycode-toascii-verification",
  "version": "1.0.0",
  "description": "verify punycode.toASCII in pkg:npm/punycode@2.3.1",
  "main": "index.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "dependencies": {
    "punycode": "2.3.1"
  },
  "private": true,
  "license": "MIT-0"
}

{
  "schemaVersion": 1,
  "goal": "verify punycode.toASCII in pkg:npm/punycode@2.3.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/punycode@2.3.1"
  ],
  "symbols": [
    "punycode.toASCII"
  ],
  "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 punycode = require('punycode/');
const { toASCII } = require('../index.js');

// 1. Verify punycode.toASCII converts internationalized domain names with Unicode characters to Punycode ASCII encoding
assert.strictEqual(
  punycode.toASCII('mañana.com'),
  'xn--maana-pta.com',
  'punycode.toASCII should convert internationalized domain names'
);

assert.strictEqual(
  punycode.toASCII('bücher.example.com'),
  'xn--bcher-kva.example.com',
  'punycode.toASCII should convert German umlauts in domain names'
);

assert.strictEqual(
  toASCII('mañana.com'),
  'xn--maana-pta.com',
  'toASCII exported function should convert internationalized domain names'
);

// 2. Verify punycode.toASCII preserves ASCII-only domain names
assert.strictEqual(
  punycode.toASCII('example.com'),
  'example.com',
  'punycode.toASCII should leave ASCII domains unchanged'
);

assert.strictEqual(
  toASCII('example.com'),
  'example.com',
  'toASCII exported function should leave ASCII domains unchanged'
);

// 3. Verify punycode.toASCII handles symbols
assert.strictEqual(
  punycode.toASCII('☃-⌘.com'),
  'xn----dqo34k.com',
  'punycode.toASCII should convert Unicode symbol domains'
);

console.log('Contract assertions passed.');