responselike 2.0.1: ResponseLike

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 ResponseLike in pkg:npm/responselike@2.0.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/responselike@2.0.1
Demonstrate these symbols/APIs:
  - ResponseLike

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:f0eccf43dbe6da668328359c7d394a5dd5fa6f2a1f20be1045ce685208aba6b0","contract":["ResponseLike constructs a response stream with statusCode, lowercased headers, body buffer, and url","ResponseLike behaves as a readable stream yielding the body buffer","ResponseLike normalizes header keys to lowercase","ResponseLike throws TypeError when constructor arguments are invalid"],"goal":"verify ResponseLike in pkg:npm/responselike@2.0.1","kind":"HOW","packages":["pkg:npm/responselike@2.0.1"],"schemaVersion":1,"symbols":["ResponseLike"]},"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/responselike@2.0.1"],"schemaVersion":1,"subject":"pkg:npm/responselike@2.0.1","symbols":["ResponseLike"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-responselike",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-responselike",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "responselike": "2.0.1"
      }
    },
    "node_modules/lowercase-keys": {
      "version": "2.0.0",
      "resolved": "https://registry.npmjs.org/lowercase-keys/-/lowercase-keys-2.0.0.tgz",
      "integrity": "sha512-tqNXrS78oMOE73NMxK4EMLQsQowWf8jKooH9g7xPavRT706R6bkQJ6DY2Te7QukaZsulxa30wQ7bk0pm4XiHmA==",
      "license": "MIT",
      "engines": {
        "node": ">=8"
      }
    },
    "node_modules/responselike": {
      "version": "2.0.1",
      "resolved": "https://registry.npmjs.org/responselike/-/responselike-2.0.1.tgz",
      "integrity": "sha512-4gl03wn3hj1HP3yzgdI7d3lCkF95F21Pz4BPGvKHinyQzALR5CapwC8yIi0Rh58DEMQ/SguC03wFj2k0M/mHhw==",
      "license": "MIT",
      "dependencies": {
        "lowercase-keys": "^2.0.0"
      },
      "funding": {
        "url": "https://github.com/sponsors/sindresorhus"
      }
    }
  }
}

{
  "name": "sample-responselike",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "license": "MIT-0",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "responselike": "2.0.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify ResponseLike in pkg:npm/responselike@2.0.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/responselike@2.0.1"
  ],
  "symbols": [
    "ResponseLike"
  ]
}

import ResponseLike from 'responselike';

/**
 * Creates a mock response object wrapping status code, headers, body buffer, and URL.
 * @param {number} statusCode HTTP status code
 * @param {Record<string, string>} headers HTTP response headers
 * @param {Buffer} body Response payload buffer
 * @param {string} url Request URL
 * @returns {ResponseLike} ResponseLike stream instance
 */
export function createResponse(statusCode, headers, body, url) {
  return new ResponseLike(statusCode, headers, body, url);
}

/**
 * Reads all data from a ResponseLike stream into a single Buffer.
 * @param {ResponseLike} response The response stream
 * @returns {Promise<Buffer>} Resolved buffer payload
 */
export async function readResponseBody(response) {
  const chunks = [];
  for await (const chunk of response) {
    chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk));
  }
  return Buffer.concat(chunks);
}

export { ResponseLike };
export default ResponseLike;

import assert from 'node:assert/strict';
import ResponseLike from 'responselike';
import { createResponse, readResponseBody } from '../src/index.mjs';

// 1. ResponseLike constructs a response stream with statusCode, lowercased headers, body buffer, and url
{
  const body = Buffer.from('hello world');
  const headers = { 'Content-Type': 'text/plain', 'X-Custom-Header': 'value' };
  const res = new ResponseLike(200, headers, body, 'https://example.com/api');

  assert.equal(res.statusCode, 200);
  assert.deepEqual(res.headers, {
    'content-type': 'text/plain',
    'x-custom-header': 'value'
  });
  assert.equal(res.body, body);
  assert.equal(res.url, 'https://example.com/api');
}

// 2. ResponseLike behaves as a readable stream yielding the body buffer
{
  const body = Buffer.from(JSON.stringify({ message: 'ok' }));
  const res = createResponse(200, { 'Content-Type': 'application/json' }, body, 'https://example.com/data');

  const consumed = await readResponseBody(res);
  assert.deepEqual(consumed, body);
  assert.equal(consumed.toString('utf8'), '{"message":"ok"}');
}

// 3. ResponseLike normalizes header keys to lowercase
{
  const headers = {
    'AUTHORIZATION': 'Bearer token',
    'Cache-Control': 'no-cache',
    'x-REQUEST-id': '12345'
  };
  const res = new ResponseLike(200, headers, Buffer.from(''), 'https://example.com');
  assert.equal(res.headers['authorization'], 'Bearer token');
  assert.equal(res.headers['cache-control'], 'no-cache');
  assert.equal(res.headers['x-request-id'], '12345');
}

// 4. ResponseLike throws TypeError when constructor arguments are invalid
{
  const validBody = Buffer.from('data');
  const validHeaders = {};

  // statusCode not number
  assert.throws(() => new ResponseLike('200', validHeaders, validBody, 'https://example.com'), {
    name: 'TypeError',
    message: 'Argument `statusCode` should be a number'
  });

  // headers not object
  assert.throws(() => new ResponseLike(200, 'headers', validBody, 'https://example.com'), {
    name: 'TypeError',
    message: 'Argument `headers` should be an object'
  });

  // body not buffer
  assert.throws(() => new ResponseLike(200, validHeaders, 'not-a-buffer', 'https://example.com'), {
    name: 'TypeError',
    message: 'Argument `body` should be a buffer'
  });

  // url not string
  assert.throws(() => new ResponseLike(200, validHeaders, validBody, 12345), {
    name: 'TypeError',
    message: 'Argument `url` should be a string'
  });
}

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