etag 1.8.1

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/etag@1.8.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/etag@1.8.1
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:sha256:6fcdeb018a62a807d060fed6847840ddaaa8b5ae437fe17c8c54ad55b9957321","constraints":{"executionContext":"node"},"contract":["etag generates strong quoted ETag for strings and Buffers","etag generates weak ETag with W/ prefix when weak option is enabled","etag generates weak ETag for fs.Stats by default and strong ETag when weak is false","isFresh correctly validates entity against If-None-Match headers"],"goal":"verify pkg:npm/etag@1.8.1","kind":"HOW","packages":["pkg:npm/etag@1.8.1"],"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/etag@1.8.1"],"schemaVersion":1,"verifierAdapter":"node-typescript@1"}

{
  "name": "etag-sample",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "etag-sample",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "etag": "1.8.1"
      }
    },
    "node_modules/etag": {
      "version": "1.8.1",
      "resolved": "https://registry.npmjs.org/etag/-/etag-1.8.1.tgz",
      "integrity": "sha512-aIL5Fx7mawVa300al2BnEE4iNvo1qETxLrPI/o05L7z6go7fCw1J6EQmbK4FmJ2AS7kgVF/KEZWufBfdClMcPg==",
      "license": "MIT",
      "engines": {
        "node": ">= 0.6"
      }
    }
  }
}

{
  "name": "etag-sample",
  "version": "1.0.0",
  "description": "Minimal sample verifying pkg:npm/etag@1.8.1",
  "main": "src/index.js",
  "license": "MIT-0",
  "dependencies": {
    "etag": "1.8.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/etag@1.8.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/etag@1.8.1"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

const etag = require('etag');

function generateStringETag(entity, options) {
  return etag(entity, options);
}

function generateStatsETag(stats, options) {
  return etag(stats, options);
}

function isFresh(entity, ifNoneMatch, options) {
  const currentETag = etag(entity, options);
  if (!ifNoneMatch) {
    return false;
  }
  if (ifNoneMatch === '*') {
    return true;
  }
  const tags = ifNoneMatch.split(',').map((t) => t.trim());
  return tags.includes(currentETag);
}

module.exports = {
  generateStringETag,
  generateStatsETag,
  isFresh,
};

const assert = require('node:assert/strict');
const fs = require('node:fs');
const { generateStringETag, generateStatsETag, isFresh } = require('../src/index.js');

// Contract 1: etag generates strong quoted ETag for strings and Buffers
const strTag = generateStringETag('hello world');
assert.strictEqual(strTag, '"b-Kq5sNclPz7QV2+lfQIuc6R7oRu0"');
assert.strictEqual(generateStringETag(Buffer.from('hello world')), strTag);
assert.strictEqual(generateStringETag(''), '"0-2jmj7l5rSw0yVb/vlWAYkK/YBwk"');

// Contract 2: etag generates weak ETag with W/ prefix when weak option is enabled
const weakTag = generateStringETag('hello world', { weak: true });
assert.strictEqual(weakTag, 'W/"b-Kq5sNclPz7QV2+lfQIuc6R7oRu0"');
assert.ok(weakTag.startsWith('W/'));

// Contract 3: etag generates weak ETag for fs.Stats by default and strong ETag when weak is false
const stats = fs.statSync(__filename);
const statsWeakTag = generateStatsETag(stats);
assert.ok(statsWeakTag.startsWith('W/'));
assert.match(statsWeakTag, /^W\/"[0-9a-f]+-[0-9a-f]+"$/);

const statsStrongTag = generateStatsETag(stats, { weak: false });
assert.ok(!statsStrongTag.startsWith('W/'));
assert.match(statsStrongTag, /^"[0-9a-f]+-[0-9a-f]+"$/);

// Contract 4: isFresh correctly validates entity against If-None-Match headers
assert.strictEqual(isFresh('hello world', '"b-Kq5sNclPz7QV2+lfQIuc6R7oRu0"'), true);
assert.strictEqual(isFresh('hello world', '"other-tag", "b-Kq5sNclPz7QV2+lfQIuc6R7oRu0"'), true);
assert.strictEqual(isFresh('hello world', '*'), true);
assert.strictEqual(isFresh('hello world', '"different-etag"'), false);

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