b4a 1.8.1: isBuffer

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 b4a.isBuffer in pkg:npm/b4a@1.8.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/b4a@1.8.1
Demonstrate these symbols/APIs:
  - b4a.isBuffer

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:e48cd7077da106f82f9f63279df7ae16eddea4430597355ca940fc018f55ed27","contract":["assert b4a.isBuffer returns true for Buffer and Uint8Array instances","assert b4a.isBuffer returns false for non-buffer types including ArrayBuffer, typed arrays, primitives, and objects","assert assertBuffer helper validates buffer types and throws TypeError on invalid input"],"goal":"verify b4a.isBuffer in pkg:npm/b4a@1.8.1","kind":"HOW","packages":["pkg:npm/b4a@1.8.1"],"schemaVersion":1,"symbols":["b4a.isBuffer"]},"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/b4a@1.8.1"],"schemaVersion":1,"subject":"pkg:npm/b4a@1.8.1","symbols":["b4a.isBuffer"],"verifierAdapter":"node-typescript@1"}

const b4a = require('b4a');

/**
 * Checks whether the given value is a valid Buffer or Uint8Array instance.
 *
 * @param {*} value - The value to check.
 * @returns {boolean} True if value is a Buffer or Uint8Array, false otherwise.
 */
function isBuffer(value) {
  return b4a.isBuffer(value);
}

/**
 * Validates that an input is a buffer, returning the buffer or throwing a TypeError.
 *
 * @param {*} value - The value to validate.
 * @returns {Uint8Array} The verified buffer.
 * @throws {TypeError} If the value is not a buffer or Uint8Array.
 */
function assertBuffer(value) {
  if (!b4a.isBuffer(value)) {
    throw new TypeError('Expected a Buffer or Uint8Array');
  }
  return value;
}

module.exports = {
  isBuffer,
  assertBuffer,
  b4a,
};

{
  "name": "sample-b4a-is-buffer",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-b4a-is-buffer",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "b4a": "1.8.1"
      }
    },
    "node_modules/b4a": {
      "version": "1.8.1",
      "resolved": "https://registry.npmjs.org/b4a/-/b4a-1.8.1.tgz",
      "integrity": "sha512-aiqre1Nr0B/6DgE2N5vwTc+2/oQZ4Wh1t4NznYY4E00y8LCt6NqdRv81so00oo27D8MVKTpUa/MwUUtBLXCoDw==",
      "license": "Apache-2.0",
      "peerDependencies": {
        "react-native-b4a": "*"
      },
      "peerDependenciesMeta": {
        "react-native-b4a": {
          "optional": true
        }
      }
    }
  }
}

{
  "name": "sample-b4a-is-buffer",
  "version": "1.0.0",
  "description": "Clean-room sample verifying b4a.isBuffer in b4a",
  "main": "index.js",
  "license": "MIT-0",
  "dependencies": {
    "b4a": "1.8.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify b4a.isBuffer in pkg:npm/b4a@1.8.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/b4a@1.8.1"
  ],
  "symbols": [
    "b4a.isBuffer"
  ]
}

import assert from 'node:assert';
import b4a from 'b4a';
import { isBuffer, assertBuffer } from '../index.js';

// 1. Assert b4a.isBuffer returns true for Node.js Buffer and Uint8Array instances
const nodeBuf = Buffer.alloc(16);
const uint8Arr = new Uint8Array(16);
const b4aAllocBuf = b4a.alloc(16);
const b4aFromBuf = b4a.from('test data');

assert.strictEqual(isBuffer(nodeBuf), true, 'b4a.isBuffer must return true for Buffer instances');
assert.strictEqual(isBuffer(uint8Arr), true, 'b4a.isBuffer must return true for Uint8Array instances');
assert.strictEqual(isBuffer(b4aAllocBuf), true, 'b4a.isBuffer must return true for b4a.alloc buffers');
assert.strictEqual(isBuffer(b4aFromBuf), true, 'b4a.isBuffer must return true for b4a.from buffers');

// 2. Assert b4a.isBuffer returns false for non-buffer types (ArrayBuffer, other typed arrays, strings, objects, primitives)
assert.strictEqual(isBuffer(new ArrayBuffer(16)), false, 'b4a.isBuffer must return false for ArrayBuffer');
assert.strictEqual(isBuffer(new Uint16Array(16)), false, 'b4a.isBuffer must return false for Uint16Array');
assert.strictEqual(isBuffer(new Int32Array(16)), false, 'b4a.isBuffer must return false for Int32Array');
assert.strictEqual(isBuffer([]), false, 'b4a.isBuffer must return false for Array');
assert.strictEqual(isBuffer([1, 2, 3]), false, 'b4a.isBuffer must return false for numeric Array');
assert.strictEqual(isBuffer('hello world'), false, 'b4a.isBuffer must return false for string');
assert.strictEqual(isBuffer(12345), false, 'b4a.isBuffer must return false for number');
assert.strictEqual(isBuffer({}), false, 'b4a.isBuffer must return false for plain object');
assert.strictEqual(isBuffer(null), false, 'b4a.isBuffer must return false for null');
assert.strictEqual(isBuffer(undefined), false, 'b4a.isBuffer must return false for undefined');

// 3. Assert assertBuffer succeeds on buffers and throws TypeError on non-buffers
assert.strictEqual(assertBuffer(uint8Arr), uint8Arr, 'assertBuffer must return buffer when valid');
assert.throws(
  () => assertBuffer('invalid'),
  { name: 'TypeError', message: 'Expected a Buffer or Uint8Array' },
  'assertBuffer must throw TypeError for non-buffer values'
);

console.log('All b4a.isBuffer contract assertions passed.');