bare-buffer 3.7.0: Buffer.prototype.writeUInt16BE

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 Buffer.prototype.writeUInt16BE in pkg:npm/bare-buffer@3.7.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/bare-buffer@3.7.0
Demonstrate these symbols/APIs:
  - Buffer.prototype.writeUInt16BE

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:b4f25230567cbe34cd222410fc02f31c5beba65fda524f171494fffdb1dced03","contract":["Buffer.prototype.writeUInt16BE is a function aliasing Buffer.prototype.writeUint16BE","buf.writeUInt16BE(value) defaults to offset 0, writes big-endian 16-bit unsigned integer, and returns offset + 2","buf.writeUInt16BE(value, offset) writes 16-bit big-endian unsigned integer at specified byte offset","buf.writeUInt16BE masks values exceeding 16 bits to lower 16 bits","buf.writeUInt16BE throws RangeError when offset is out of bounds, negative, or non-integer","buf.writeUInt16BE throws TypeError when offset is not a number"],"goal":"verify Buffer.prototype.writeUInt16BE in pkg:npm/bare-buffer@3.7.0","kind":"HOW","packages":["pkg:npm/bare-buffer@3.7.0"],"schemaVersion":1,"symbols":["Buffer.prototype.writeUInt16BE"]},"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/bare-buffer@3.7.0"],"schemaVersion":1,"subject":"pkg:npm/bare-buffer@3.7.0","symbols":["Buffer.prototype.writeUInt16BE"],"verifierAdapter":"node-typescript@1"}

import { createRequire } from 'node:module';
import path from 'node:path';

const require = createRequire(import.meta.url);

// Ensure binding is available in Node.js environments where require.addon is absent
if (typeof Bare === 'undefined') {
  const nodeBuffer = globalThis.Buffer;
  const mockBinding = {
    constants: {
      MAX_LENGTH: 2147483647,
      MAX_STRING_LENGTH: 1073741799
    },
    alloc(size) { return new ArrayBuffer(size); },
    allocUnsafe(size) { return new ArrayBuffer(size); },
    compare(bufA, offA, lenA, bufB, offB, lenB) {
      const a = nodeBuffer.from(bufA, offA, lenA);
      const b = nodeBuffer.from(bufB, offB, lenB);
      return a.compare(b);
    },
    toStringHex(buf, offset, len) {
      return nodeBuffer.from(buf, offset, len).toString('hex');
    },
    writeHex(buf, offset, len, string) {
      return nodeBuffer.from(buf, offset, len).write(string, 0, len, 'hex');
    },
    toStringBase64(buf, offset, len) {
      return nodeBuffer.from(buf, offset, len).toString('base64');
    },
    writeBase64(buf, offset, len, string) {
      return nodeBuffer.from(buf, offset, len).write(string, 0, len, 'base64');
    },
    toStringBase64URL(buf, offset, len) {
      return nodeBuffer.from(buf, offset, len).toString('base64url');
    },
    writeBase64URL(buf, offset, len) {
      return nodeBuffer.from(buf, offset, len).write(string, 0, len, 'base64url');
    },
    toStringUTF8(buf, offset, len) {
      return nodeBuffer.from(buf, offset, len).toString('utf8');
    },
    writeUTF8(buf, offset, len, string) {
      return nodeBuffer.from(buf, offset, len).write(string, 0, len, 'utf8');
    },
    validateUTF8(buf, offset, len) {
      return nodeBuffer.isUtf8 ? nodeBuffer.isUtf8(nodeBuffer.from(buf, offset, len)) : true;
    },
    byteLengthUTF8(string) {
      return nodeBuffer.byteLength(string, 'utf8');
    },
    toStringUTF16LE(buf, offset, len) {
      return nodeBuffer.from(buf, offset, len).toString('utf16le');
    },
    writeUTF16LE(buf, offset, len, string) {
      return nodeBuffer.from(buf, offset, len).write(string, 0, len, 'utf16le');
    },
    toStringLatin1(buf, offset, len) {
      return nodeBuffer.from(buf, offset, len).toString('latin1');
    },
    writeLatin1(buf, offset, len, string) {
      return nodeBuffer.from(buf, offset, len).write(string, 0, len, 'latin1');
    },
    indexOf(bufA, offA, lenA, bufB, offB, lenB, byteOffset) {
      const a = nodeBuffer.from(bufA, offA, lenA);
      const b = nodeBuffer.from(bufB, offB, lenB);
      return a.indexOf(b, byteOffset);
    },
    lastIndexOf(bufA, offA, lenA, bufB, offB, lenB, byteOffset) {
      const a = nodeBuffer.from(bufA, offA, lenA);
      const b = nodeBuffer.from(bufB, offB, lenB);
      return a.lastIndexOf(b, byteOffset);
    },
    swap16(buf, offset, len) {
      nodeBuffer.from(buf, offset, len).swap16();
    },
    swap32(buf, offset, len) {
      nodeBuffer.from(buf, offset, len).swap32();
    },
    swap64(buf, offset, len) {
      nodeBuffer.from(buf, offset, len).swap64();
    }
  };

  const mainPath = require.resolve('bare-buffer');
  const bindingPath = path.join(path.dirname(mainPath), 'binding.js');
  require.cache[bindingPath] = {
    id: bindingPath,
    filename: bindingPath,
    loaded: true,
    exports: mockBinding
  };
}

const Buffer = require('bare-buffer');

export function writeUInt16BE(buffer, value, offset = 0) {
  return buffer.writeUInt16BE(value, offset);
}

export function writeUInt16BEArray(buffer, values, offset = 0) {
  let currentOffset = offset;
  for (const val of values) {
    currentOffset = buffer.writeUInt16BE(val, currentOffset);
  }
  return currentOffset;
}

export { Buffer };
export default Buffer;

{
  "name": "sample-bare-buffer-write-uint16-be",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-bare-buffer-write-uint16-be",
      "version": "1.0.0",
      "dependencies": {
        "bare-buffer": "3.7.0"
      }
    },
    "node_modules/bare-buffer": {
      "version": "3.7.0",
      "resolved": "https://registry.npmjs.org/bare-buffer/-/bare-buffer-3.7.0.tgz",
      "integrity": "sha512-/xRTbBuLis7sE3Izii0A0yOm+WqH1/gh12UVqkpIAOLZ4gWluyK0THbGB+UysKI8ZBjcZ+MaEs9Auxcyiz2yLA==",
      "license": "Apache-2.0",
      "engines": {
        "bare": ">=1.20.0"
      }
    }
  }
}

{
  "name": "sample-bare-buffer-write-uint16-be",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "dependencies": {
    "bare-buffer": "3.7.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify Buffer.prototype.writeUInt16BE in pkg:npm/bare-buffer@3.7.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/bare-buffer@3.7.0"
  ],
  "symbols": [
    "Buffer.prototype.writeUInt16BE"
  ]
}

import assert from 'node:assert/strict';
import Buffer, { writeUInt16BE, writeUInt16BEArray } from '../index.js';

// 1. Buffer.prototype.writeUInt16BE exists and aliases writeUint16BE
assert.strictEqual(typeof Buffer.prototype.writeUInt16BE, 'function', 'writeUInt16BE must be a prototype method');
assert.strictEqual(Buffer.prototype.writeUInt16BE, Buffer.prototype.writeUint16BE, 'writeUInt16BE must alias writeUint16BE');

// 2. Default offset is 0 and writes big-endian 16-bit unsigned integer
const buf1 = Buffer.alloc(4);
const ret1 = buf1.writeUInt16BE(0x1234);
assert.strictEqual(ret1, 2, 'Default offset should return offset + 2 (2)');
assert.strictEqual(buf1[0], 0x12, 'First byte must be high byte 0x12');
assert.strictEqual(buf1[1], 0x34, 'Second byte must be low byte 0x34');
assert.strictEqual(buf1.readUInt16BE(0), 0x1234, 'Read back must match 0x1234');

// 3. Big-endian byte order verification across numeric boundaries
const maxBuf = Buffer.alloc(2);
maxBuf.writeUInt16BE(65535, 0);
assert.deepStrictEqual(Array.from(maxBuf), [0xff, 0xff], '65535 should write [0xff, 0xff]');

const zeroBuf = Buffer.alloc(2);
zeroBuf.writeUInt16BE(0, 0);
assert.deepStrictEqual(Array.from(zeroBuf), [0x00, 0x00], '0 should write [0x00, 0x00]');

const midBuf = Buffer.alloc(2);
midBuf.writeUInt16BE(32768, 0);
assert.deepStrictEqual(Array.from(midBuf), [0x80, 0x00], '32768 should write [0x80, 0x00]');

const asymmetryBuf = Buffer.alloc(2);
asymmetryBuf.writeUInt16BE(0x0102, 0);
assert.deepStrictEqual(Array.from(asymmetryBuf), [0x01, 0x02], '0x0102 must write [0x01, 0x02], not little-endian [0x02, 0x01]');

// 4. Writing at arbitrary positive offsets in a larger buffer
const multiBuf = Buffer.alloc(6);
const ret2 = multiBuf.writeUInt16BE(0x1234, 1);
assert.strictEqual(ret2, 3, 'Offset 1 write should return 3');
const ret3 = multiBuf.writeUInt16BE(0x5678, 3);
assert.strictEqual(ret3, 5, 'Offset 3 write should return 5');
assert.deepStrictEqual(Array.from(multiBuf), [0x00, 0x12, 0x34, 0x56, 0x78, 0x00], 'Multi-offset write layout must match');

// 5. Overflow masking (values exceeding 16 bits truncate to lower 16 bits)
const maskBuf = Buffer.alloc(2);
maskBuf.writeUInt16BE(0x123456, 0);
assert.deepStrictEqual(Array.from(maskBuf), [0x34, 0x56], '0x123456 should be masked to 0x3456');

// 6. Helper function wrappers
const helperBuf = Buffer.alloc(4);
assert.strictEqual(writeUInt16BE(helperBuf, 0xabcd, 1), 3, 'writeUInt16BE helper should return 3');
assert.deepStrictEqual(Array.from(helperBuf.subarray(1, 3)), [0xab, 0xcd], 'writeUInt16BE helper should write correct bytes');

const seqBuf = Buffer.alloc(6);
const finalOffset = writeUInt16BEArray(seqBuf, [10, 20, 30], 0);
assert.strictEqual(finalOffset, 6, 'writeUInt16BEArray should return final offset 6');
assert.deepStrictEqual(Array.from(seqBuf), [0x00, 0x0a, 0x00, 0x14, 0x00, 0x1e], 'writeUInt16BEArray should write uint16 BE sequence');

// 7. RangeError thrown on bounds violation
const smallBuf = Buffer.alloc(2);
assert.throws(() => {
  smallBuf.writeUInt16BE(0x1234, 1);
}, { name: 'RangeError' }, 'Offset with less than 2 bytes remaining must throw RangeError');

assert.throws(() => {
  smallBuf.writeUInt16BE(0x1234, 2);
}, { name: 'RangeError' }, 'Offset at end of buffer must throw RangeError');

assert.throws(() => {
  smallBuf.writeUInt16BE(0x1234, -1);
}, { name: 'RangeError' }, 'Negative offset must throw RangeError');

const emptyBuf = Buffer.alloc(0);
assert.throws(() => {
  emptyBuf.writeUInt16BE(0x1234, 0);
}, { name: 'RangeError' }, 'Writing to empty buffer must throw RangeError');

assert.throws(() => {
  smallBuf.writeUInt16BE(0x1234, 0.5);
}, { name: 'RangeError' }, 'Non-integer offset must throw RangeError');

// 8. TypeError thrown on non-numeric offset type
assert.throws(() => {
  smallBuf.writeUInt16BE(0x1234, '0');
}, { name: 'TypeError' }, 'String offset must throw TypeError');

assert.throws(() => {
  smallBuf.writeUInt16BE(0x1234, null);
}, { name: 'TypeError' }, 'Null offset must throw TypeError');

console.log('Contract verification finished successfully.');