lru-cache 6.0.0

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/lru-cache@6.0.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/lru-cache@6.0.0

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:sha256:47e1a2affbbb295cb66ba426707a9aaee4bcd3db7fed3b64b5c386801487e487","contract":["cache.set(key, value) and cache.get(key) store and retrieve values","cache.has(key) returns true for existing keys and false for missing keys","cache.del(key) removes the key and reduces itemCount","cache evicts the least recently used item when max capacity is exceeded","cache.get(key) updates recency so the accessed item is not evicted next","cache.reset() clears all cached entries and resets itemCount to 0","cache.keys() and cache.values() return active keys and values in recency order"],"goal":"verify pkg:npm/lru-cache@6.0.0","kind":"HOW","packages":["pkg:npm/lru-cache@6.0.0"],"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/lru-cache@6.0.0"],"schemaVersion":1,"subject":"pkg:npm/lru-cache@6.0.0","verifierAdapter":"node-typescript@1"}

import LRU from 'lru-cache';

export function createCache(options) {
  return new LRU(options);
}

{
  "name": "sample-lru-cache",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-lru-cache",
      "version": "1.0.0",
      "dependencies": {
        "lru-cache": "6.0.0"
      }
    },
    "node_modules/lru-cache": {
      "version": "6.0.0",
      "resolved": "https://registry.npmjs.org/lru-cache/-/lru-cache-6.0.0.tgz",
      "integrity": "sha512-Jo6dJ04CmSjuznwJSS3pUeWmd/H0ffTlkXXgwZi+eq1UCmqQwCh+eLsYOYCwY991i2Fah4h1BEMCx4qThGbsiA==",
      "license": "ISC",
      "dependencies": {
        "yallist": "^4.0.0"
      },
      "engines": {
        "node": ">=10"
      }
    },
    "node_modules/yallist": {
      "version": "4.0.0",
      "resolved": "https://registry.npmjs.org/yallist/-/yallist-4.0.0.tgz",
      "integrity": "sha512-3wdGidZyq5PB084XLES5TpOSRA3wjXAlIWMhum2kRcv/41Sn2emQ0dycQW4uZXLejwKvg6EsvbdlVL+FYEct7A==",
      "license": "ISC"
    }
  }
}

{
  "name": "sample-lru-cache",
  "version": "1.0.0",
  "description": "Clean-room verification sample for lru-cache",
  "type": "module",
  "private": true,
  "dependencies": {
    "lru-cache": "6.0.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/lru-cache@6.0.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/lru-cache@6.0.0"
  ]
}

import assert from 'node:assert/strict';
import LRU from 'lru-cache';
import { createCache } from '../index.mjs';

// 1. cache.set(key, value) and cache.get(key) store and retrieve values
const cache = createCache({ max: 3 });
cache.set('a', 'alpha');
cache.set('b', 'beta');
assert.equal(cache.get('a'), 'alpha');
assert.equal(cache.get('b'), 'beta');
assert.equal(cache.get('c'), undefined);

// 2. cache.has(key) returns true for existing keys and false for missing keys
assert.equal(cache.has('a'), true);
assert.equal(cache.has('b'), true);
assert.equal(cache.has('missing'), false);

// 3. cache.del(key) removes the key and reduces itemCount
assert.equal(cache.itemCount, 2);
cache.del('b');
assert.equal(cache.has('b'), false);
assert.equal(cache.get('b'), undefined);
assert.equal(cache.itemCount, 1);

// 4. cache evicts the least recently used item when max capacity is exceeded
const smallCache = new LRU({ max: 2 });
smallCache.set('x', 1);
smallCache.set('y', 2);
smallCache.set('z', 3);
assert.equal(smallCache.has('x'), false);
assert.equal(smallCache.get('y'), 2);
assert.equal(smallCache.get('z'), 3);
assert.equal(smallCache.itemCount, 2);

// 5. cache.get(key) updates recency so the accessed item is not evicted next
const lruCache = new LRU({ max: 2 });
lruCache.set('first', '1');
lruCache.set('second', '2');
lruCache.get('first');
lruCache.set('third', '3');
assert.equal(lruCache.has('second'), false);
assert.equal(lruCache.has('first'), true);
assert.equal(lruCache.has('third'), true);

// 6. cache.reset() clears all cached entries and resets itemCount to 0
lruCache.reset();
assert.equal(lruCache.itemCount, 0);
assert.equal(lruCache.has('first'), false);
assert.equal(lruCache.has('third'), false);

// 7. cache.keys() and cache.values() return active keys and values in recency order
const iterCache = new LRU({ max: 3 });
iterCache.set('k1', 'v1');
iterCache.set('k2', 'v2');
iterCache.set('k3', 'v3');
assert.deepEqual(Array.from(iterCache.keys()), ['k3', 'k2', 'k1']);
assert.deepEqual(Array.from(iterCache.values()), ['v3', 'v2', 'v1']);

console.log('All lru-cache@6.0.0 contract assertions passed.');