fresh 2.0.0

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/fresh@2.0.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/fresh@2.0.0

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:f8aa366ce0acad548bde72db92105d45ed260fe9a6f4c004e3f20cd9b8121604","contract":["fresh(reqHeaders, resHeaders) returns false for unconditional requests without if-modified-since or if-none-match","fresh(reqHeaders, resHeaders) returns false when Cache-Control header contains no-cache even if ETags match","fresh(reqHeaders, resHeaders) returns true when if-none-match exactly matches the response etag","fresh(reqHeaders, resHeaders) returns true when matching weak ETags like W/\"123\" and \"123\"","fresh(reqHeaders, resHeaders) returns true when if-none-match is wildcard *","fresh(reqHeaders, resHeaders) returns true when if-modified-since is at or after response last-modified date","fresh(reqHeaders, resHeaders) prioritizes if-none-match over if-modified-since when both are present"],"goal":"verify pkg:npm/fresh@2.0.0","kind":"HOW","packages":["pkg:npm/fresh@2.0.0"],"schemaVersion":1},"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/fresh@2.0.0"],"schemaVersion":1,"verifierAdapter":"node-typescript@1"}

import fresh from 'fresh';

export function isResponseFresh(reqHeaders, resHeaders) {
  return fresh(reqHeaders, resHeaders);
}

{
  "name": "sample-fresh",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-fresh",
      "version": "1.0.0",
      "dependencies": {
        "fresh": "2.0.0"
      }
    },
    "node_modules/fresh": {
      "version": "2.0.0",
      "resolved": "https://registry.npmjs.org/fresh/-/fresh-2.0.0.tgz",
      "integrity": "sha512-Rx/WycZ60HOaqLKAi6cHRKKI7zxWbJ31MhntmtwMoaTeF7XFH9hhBp8vITaMidfljRQ6eYWCKkaTK+ykVJHP2A==",
      "license": "MIT",
      "engines": {
        "node": ">= 0.8"
      }
    }
  }
}

{
  "name": "sample-fresh",
  "version": "1.0.0",
  "description": "Clean-room verification sample for fresh",
  "type": "module",
  "private": true,
  "dependencies": {
    "fresh": "2.0.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/fresh@2.0.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/fresh@2.0.0"
  ]
}

import assert from 'node:assert/strict';
import fresh from 'fresh';
import { isResponseFresh } from '../index.mjs';

// 1. Unconditional requests return false
assert.equal(fresh({}, {}), false);
assert.equal(isResponseFresh({ host: 'example.com' }, { etag: '"123"' }), false);

// 2. Cache-Control: no-cache returns false even when ETags match
assert.equal(fresh({ 'if-none-match': '"123"', 'cache-control': 'no-cache' }, { etag: '"123"' }), false);
assert.equal(fresh({ 'if-none-match': '"123"', 'cache-control': 'max-age=0, no-cache' }, { etag: '"123"' }), false);

// 3. Exact if-none-match match returns true
assert.equal(fresh({ 'if-none-match': '"123"' }, { etag: '"123"' }), true);
assert.equal(fresh({ 'if-none-match': '"123"' }, { etag: '"456"' }), false);
assert.equal(fresh({ 'if-none-match': '"foo", "bar"' }, { etag: '"bar"' }), true);

// 4. Weak ETag matching returns true
assert.equal(fresh({ 'if-none-match': 'W/"123"' }, { etag: '"123"' }), true);
assert.equal(fresh({ 'if-none-match': '"123"' }, { etag: 'W/"123"' }), true);
assert.equal(fresh({ 'if-none-match': 'W/"123"' }, { etag: 'W/"123"' }), true);

// 5. Wildcard * if-none-match returns true
assert.equal(fresh({ 'if-none-match': '*' }, { etag: '"anything"' }), true);
assert.equal(fresh({ 'if-none-match': '*' }, {}), true);

// 6. if-modified-since comparison
const now = new Date('2026-08-20T12:00:00Z').toUTCString();
const past = new Date('2026-08-20T11:00:00Z').toUTCString();
const future = new Date('2026-08-20T13:00:00Z').toUTCString();
assert.equal(fresh({ 'if-modified-since': now }, { 'last-modified': past }), true);
assert.equal(fresh({ 'if-modified-since': now }, { 'last-modified': now }), true);
assert.equal(fresh({ 'if-modified-since': past }, { 'last-modified': now }), false);

// 7. if-none-match takes precedence over if-modified-since
assert.equal(fresh({ 'if-none-match': '"mismatch"', 'if-modified-since': future }, { etag: '"actual"', 'last-modified': past }), false);
assert.equal(fresh({ 'if-none-match': '"match"', 'if-modified-since': past }, { etag: '"match"', 'last-modified': future }), true);

console.log('All fresh@2.0.0 contract assertions passed.');