fast-fifo 1.3.2: FIFO queue push, shift, isEmpty, and clear operations

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: FIFO queue push, shift, isEmpty, and clear operations
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/fast-fifo@1.3.2
Demonstrate these symbols/APIs:
  - FIFO.clear
  - FIFO.isEmpty
  - FIFO.push
  - FIFO.shift

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:sha256:61cd798d07f97c09679501adc7f445ec946640597456cfd1cbc8e9025a7d375d","contract":["FIFO instantiates an empty queue with length 0 and isEmpty returning true","FIFO push adds elements to the queue in FIFO order and updates length","FIFO shift removes and returns elements in first-in first-out order until empty","FIFO clear resets queue state and length back to zero"],"goal":"FIFO queue push, shift, isEmpty, and clear operations","kind":"HOW","packages":["pkg:npm/fast-fifo@1.3.2"],"schemaVersion":1,"symbols":["FIFO.clear","FIFO.isEmpty","FIFO.push","FIFO.shift"]},"contractCommand":["node","test/contract.cjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/fast-fifo@1.3.2"],"schemaVersion":1,"subject":"pkg:npm/fast-fifo@1.3.2","symbols":["FIFO.clear","FIFO.isEmpty","FIFO.push","FIFO.shift"],"verifierAdapter":"node-typescript@1"}

'use strict';

const FIFO = require('fast-fifo');

/**
 * Creates a new FastFIFO instance.
 * @param {number} [hwm=16] - Initial buffer capacity / high water mark.
 * @returns {FIFO} A new FIFO queue instance.
 */
function createQueue(hwm) {
  return new FIFO(hwm);
}

module.exports = {
  FIFO,
  createQueue
};

{
  "name": "sample-fast-fifo",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-fast-fifo",
      "version": "1.0.0",
      "dependencies": {
        "fast-fifo": "1.3.2"
      }
    },
    "node_modules/fast-fifo": {
      "version": "1.3.2",
      "resolved": "https://registry.npmjs.org/fast-fifo/-/fast-fifo-1.3.2.tgz",
      "integrity": "sha512-/d9sfos4yxzpwkDkuN7k2SqFKtYNmCTzgfEpz82x34IM9/zc8KGxQoXg1liNC/izpRM/MBdt44Nmx41ZWqk+FQ==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-fast-fifo",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification of fast-fifo",
  "dependencies": {
    "fast-fifo": "1.3.2"
  }
}

{
  "schemaVersion": 1,
  "goal": "FIFO queue push, shift, isEmpty, and clear operations",
  "kind": "HOW",
  "packages": [
    "pkg:npm/fast-fifo@1.3.2"
  ],
  "symbols": [
    "FIFO.clear",
    "FIFO.isEmpty",
    "FIFO.push",
    "FIFO.shift"
  ]
}

'use strict';

const assert = require('node:assert/strict');
const FIFO = require('fast-fifo');
const { createQueue } = require('../index.cjs');

// Verify exports
assert.equal(typeof FIFO, 'function', 'fast-fifo should export a constructor function');
assert.equal(typeof createQueue, 'function', 'createQueue helper must be a function');

// Contract 1: FIFO instantiates an empty queue with length 0 and isEmpty returning true
const queue = createQueue();
assert.equal(queue.length, 0, 'Initial length must be 0');
assert.equal(queue.isEmpty(), true, 'isEmpty() must return true for a new queue');
assert.equal(queue.shift(), undefined, 'shift() on empty queue must return undefined');

// Contract 2: FIFO push adds elements to the queue in FIFO order and updates length
queue.push('first');
assert.equal(queue.length, 1);
assert.equal(queue.isEmpty(), false);

queue.push('second');
queue.push('third');
assert.equal(queue.length, 3);
assert.equal(queue.peek(), 'first', 'peek() must return the head item without removing it');

// Contract 3: FIFO shift removes and returns elements in first-in first-out order until empty
assert.equal(queue.shift(), 'first', 'shift() must return first pushed item');
assert.equal(queue.length, 2);
assert.equal(queue.shift(), 'second', 'shift() must return second pushed item');
assert.equal(queue.shift(), 'third', 'shift() must return third pushed item');
assert.equal(queue.length, 0);
assert.equal(queue.isEmpty(), true);
assert.equal(queue.shift(), undefined);

// Growth beyond initial high water mark
const largeQueue = createQueue(4);
for (let i = 0; i < 20; i++) {
  largeQueue.push(i);
}
assert.equal(largeQueue.length, 20);
for (let i = 0; i < 20; i++) {
  assert.equal(largeQueue.shift(), i);
}
assert.equal(largeQueue.isEmpty(), true);

// Contract 4: FIFO clear resets queue state and length back to zero
queue.push('a');
queue.push('b');
assert.equal(queue.length, 2);
queue.clear();
assert.equal(queue.length, 0, 'length must be 0 after clear()');
assert.equal(queue.isEmpty(), true, 'isEmpty() must be true after clear()');
assert.equal(queue.shift(), undefined, 'shift() must return undefined after clear()');

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