negotiator 1.0.0

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/negotiator@1.0.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/negotiator@1.0.0
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:sha256:414937b9b00faa7f700ca51fa323543f901aeb9452da676b93c01338ea7480c7","constraints":{"executionContext":"node"},"contract":["Negotiator instance parses Accept header and returns media types ordered by preference","mediaType selects the best match from an available list or returns undefined when none match","languages and language determine client preferred languages by quality weight","encodings and encoding determine supported compression algorithms from Accept-Encoding","charsets and charset select preferred character encodings from Accept-Charset"],"goal":"verify pkg:npm/negotiator@1.0.0","kind":"HOW","packages":["pkg:npm/negotiator@1.0.0"],"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/negotiator@1.0.0"],"schemaVersion":1,"verifierAdapter":"node-typescript@1"}

{
  "name": "csx-sample-negotiator",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "csx-sample-negotiator",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "negotiator": "1.0.0"
      }
    },
    "node_modules/negotiator": {
      "version": "1.0.0",
      "resolved": "https://registry.npmjs.org/negotiator/-/negotiator-1.0.0.tgz",
      "integrity": "sha512-8Ofs/AUQh8MaEcrlq5xOX0CQ9ypTF5dl78mjlMNfOK08fzpgTHQRQPBxcPlEtIw0yRpws+Zo/3r+5WRby7u3Gg==",
      "license": "MIT",
      "engines": {
        "node": ">= 0.6"
      }
    }
  }
}

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

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/negotiator@1.0.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/negotiator@1.0.0"
  ],
  "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 Negotiator = require('negotiator');

// 1. Media Type Negotiation
const mediaReq = {
  headers: {
    accept: 'text/html, application/xhtml+xml, application/xml;q=0.9, */*;q=0.8'
  }
};
const mediaNegotiator = new Negotiator(mediaReq);

const mediaTypes = mediaNegotiator.mediaTypes();
assert(Array.isArray(mediaTypes), 'mediaTypes() should return an array');
assert.strictEqual(mediaTypes[0], 'text/html', 'First preferred media type should be text/html');

const preferredMediaType = mediaNegotiator.mediaType(['application/json', 'text/html']);
assert.strictEqual(preferredMediaType, 'text/html', 'Should select text/html among available media types');

const unmatchedMediaType = mediaNegotiator.mediaType(['application/json']);
assert.strictEqual(unmatchedMediaType, 'application/json', 'Wildcard match should match application/json');

const noWildcardNegotiator = new Negotiator({
  headers: { accept: 'text/plain' }
});
assert.strictEqual(noWildcardNegotiator.mediaType(['application/json']), undefined, 'Unmatched media type should return undefined');

// 2. Language Negotiation
const langReq = {
  headers: {
    'accept-language': 'en;q=0.8, es, pt'
  }
};
const langNegotiator = new Negotiator(langReq);

const languages = langNegotiator.languages();
assert.deepStrictEqual(languages, ['es', 'pt', 'en'], 'Languages should be ordered by quality weight');

const preferredLanguage = langNegotiator.language(['en', 'fr']);
assert.strictEqual(preferredLanguage, 'en', 'Should select en when fr is not in accept-language');

const unmatchedLanguage = langNegotiator.language(['de']);
assert.strictEqual(unmatchedLanguage, undefined, 'Unmatched language should return undefined');

// 3. Encoding Negotiation
const encReq = {
  headers: {
    'accept-encoding': 'gzip, deflate;q=0.5, br;q=0.8'
  }
};
const encNegotiator = new Negotiator(encReq);

const encodings = encNegotiator.encodings();
assert(encodings.includes('gzip'), 'Encodings should include gzip');
assert(encodings.includes('br'), 'Encodings should include br');
assert(encodings.includes('deflate'), 'Encodings should include deflate');

const preferredEncoding = encNegotiator.encoding(['deflate', 'gzip']);
assert.strictEqual(preferredEncoding, 'gzip', 'Should select gzip over lower-weighted deflate');

// 4. Charset Negotiation
const charsetReq = {
  headers: {
    'accept-charset': 'iso-8859-5, unicode-1-1;q=0.8, utf-8;q=0.9'
  }
};
const charsetNegotiator = new Negotiator(charsetReq);

const charsets = charsetNegotiator.charsets();
assert.deepStrictEqual(charsets, ['iso-8859-5', 'utf-8', 'unicode-1-1'], 'Charsets should be ordered by quality weight');

const preferredCharset = charsetNegotiator.charset(['utf-8', 'iso-8859-1']);
assert.strictEqual(preferredCharset, 'utf-8', 'Should select utf-8 as preferred supported charset');

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