got 11.8.6: extend

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 got.extend in pkg:npm/got@11.8.6
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/got@11.8.6
Demonstrate these symbols/APIs:
  - got.extend

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.

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{
  "name": "sample-got-extend",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "license": "MIT-0",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "got": "11.8.6"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify got.extend in pkg:npm/got@11.8.6",
  "kind": "HOW",
  "packages": [
    "pkg:npm/got@11.8.6"
  ],
  "symbols": [
    "got.extend"
  ]
}

import got from 'got';

/**
 * Creates an extended got instance with the provided options.
 * @param {...object} options Option objects to extend got with.
 * @returns {Function} Extended got client.
 */
export function createClient(...options) {
  return got.extend(...options);
}

/**
 * Creates an extended got instance preconfigured for JSON APIs with a base URL.
 * @param {string|URL} prefixUrl Base URL for the API.
 * @param {object} [defaultHeaders={}] Default headers to include.
 * @returns {Function} Extended got client for JSON API.
 */
export function createJsonApiClient(prefixUrl, defaultHeaders = {}) {
  return got.extend({
    prefixUrl,
    headers: defaultHeaders,
    responseType: 'json'
  });
}

export { got };
export default got;

import assert from 'node:assert/strict';
import http from 'node:http';
import got, { createClient, createJsonApiClient } from '../src/index.mjs';

// 1. got.extend returns a callable Got client instance configured with defaults
{
  const client = got.extend({
    prefixUrl: 'http://127.0.0.1:8080/api',
    headers: {
      'x-custom-default': 'default-value'
    }
  });

  assert.equal(typeof client, 'function', 'client should be a function');
  assert.equal(typeof client.extend, 'function', 'client.extend should be a function');
  assert.equal(typeof client.get, 'function', 'client.get should be a function');
  assert.equal(typeof client.post, 'function', 'client.post should be a function');
  assert.equal(client.defaults.options.prefixUrl.toString(), 'http://127.0.0.1:8080/api/');
  assert.equal(client.defaults.options.headers['x-custom-default'], 'default-value');
}

// 2. got.extend merges multiple option objects into defaults
{
  const client = got.extend(
    { headers: { 'x-first': 'first' } },
    { headers: { 'x-second': 'second' }, timeout: { request: 3000 } }
  );

  assert.equal(client.defaults.options.headers['x-first'], 'first');
  assert.equal(client.defaults.options.headers['x-second'], 'second');
  assert.equal(client.defaults.options.timeout.request, 3000);
}

// 3. got.extend instances support chained extension with inherited and overridden options
{
  const parent = got.extend({
    prefixUrl: 'http://127.0.0.1:8080/v1',
    headers: {
      'x-common': 'parent-value',
      'x-override': 'initial'
    }
  });

  const child = parent.extend({
    prefixUrl: 'http://127.0.0.1:8080/v2',
    headers: {
      'x-override': 'updated',
      'x-child': 'child-only'
    }
  });

  assert.equal(child.defaults.options.prefixUrl.toString(), 'http://127.0.0.1:8080/v2/');
  assert.equal(child.defaults.options.headers['x-common'], 'parent-value');
  assert.equal(child.defaults.options.headers['x-override'], 'updated');
  assert.equal(child.defaults.options.headers['x-child'], 'child-only');
}

// 4. got.extend preserves immutability of parent client instances when extending
{
  const parentHeaders = { 'x-immutable': 'true' };
  const parent = got.extend({ headers: parentHeaders });

  const child = parent.extend({
    headers: {
      'x-immutable': 'mutated',
      'x-extra': 'added'
    }
  });

  assert.equal(parent.defaults.options.headers['x-immutable'], 'true');
  assert.equal(parent.defaults.options.headers['x-extra'], undefined);
  assert.equal(child.defaults.options.headers['x-immutable'], 'mutated');
  assert.equal(child.defaults.options.headers['x-extra'], 'added');
}

// Set up a local HTTP server for network execution contracts
const requests = [];
const server = http.createServer((req, res) => {
  requests.push({
    method: req.method,
    url: req.url,
    headers: req.headers
  });

  if (req.url === '/v1/items') {
    res.writeHead(200, { 'Content-Type': 'application/json' });
    res.end(JSON.stringify([{ id: 1, name: 'item1' }]));
  } else if (req.url === '/v1/data') {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('ok');
  } else {
    res.writeHead(404);
    res.end('Not Found');
  }
});

await new Promise((resolve) => server.listen(0, '127.0.0.1', resolve));
const port = server.address().port;
const baseUrl = `http://127.0.0.1:${port}/v1`;

try {
  // 5. got.extend sends HTTP requests with extended prefixUrl and custom headers
  {
    const client = createClient({
      prefixUrl: baseUrl,
      headers: {
        'x-client-id': 'extended-client',
        'x-trace-id': 'trace-123'
      }
    });

    const response = await client.get('data');
    assert.equal(response.statusCode, 200);
    assert.equal(response.body, 'ok');

    const lastReq = requests[requests.length - 1];
    assert.equal(lastReq.method, 'GET');
    assert.equal(lastReq.url, '/v1/data');
    assert.equal(lastReq.headers['x-client-id'], 'extended-client');
    assert.equal(lastReq.headers['x-trace-id'], 'trace-123');
  }

  // 6. createJsonApiClient helper automatically parses JSON response bodies
  {
    const apiClient = createJsonApiClient(baseUrl, { 'x-json-api': 'test' });
    const response = await apiClient.get('items');
    assert.equal(response.statusCode, 200);
    assert.deepEqual(response.body, [{ id: 1, name: 'item1' }]);

    const lastReq = requests[requests.length - 1];
    assert.equal(lastReq.url, '/v1/items');
    assert.equal(lastReq.headers['x-json-api'], 'test');
  }

  // 7. got.extend throws TypeError when options argument is not an object
  {
    assert.throws(
      () => got.extend('invalid-option-string'),
      TypeError
    );
    assert.throws(
      () => got.extend(123),
      TypeError
    );
  }
} finally {
  server.close();
}

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