p-map 7.1.1: pMapIterable

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 p-map.pMapIterable in pkg:npm/p-map@7.1.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/p-map@7.1.1
Demonstrate these symbols/APIs:
  - p-map.pMapIterable

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:a8bc5ba4d39dc33d735a41127498ad0a40f992bcfa4f3533107167eea5554ed2","contract":["pMapIterable(input, mapper, options) returns an AsyncIterable that yields mapped values in input order by default (preserveOrder: true)","When preserveOrder is false, pMapIterable yields mapped results as soon as each mapper promise resolves","Returning pMapSkip from mapper omits that element from the yielded sequence, and returning pMapStop terminates iteration and closes the source iterator","pMapIterable throws a TypeError synchronously when concurrency \u003c 1 or when backpressure \u003c concurrency"],"goal":"verify p-map.pMapIterable in pkg:npm/p-map@7.1.1","kind":"HOW","packages":["pkg:npm/p-map@7.1.1"],"schemaVersion":1,"symbols":["p-map.pMapIterable"]},"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/p-map@7.1.1"],"schemaVersion":1,"subject":"pkg:npm/p-map@7.1.1","symbols":["p-map.pMapIterable"],"verifierAdapter":"node-typescript@1"}

{
  "name": "p-map-iterable-sample",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "p-map-iterable-sample",
      "version": "1.0.0",
      "dependencies": {
        "p-map": "7.1.1"
      }
    },
    "node_modules/p-map": {
      "version": "7.1.1",
      "resolved": "https://registry.npmjs.org/p-map/-/p-map-7.1.1.tgz",
      "integrity": "sha512-6Lh3jQPLthYujSrlw6ccWXBGZTkoTCz27Hd92g79LH/kjAbgoEu0t442cCCNbegPSJsA0lwDX8z0bcKtkpA32g==",
      "license": "MIT",
      "engines": {
        "node": ">=18"
      },
      "funding": {
        "url": "https://github.com/sponsors/sindresorhus"
      }
    }
  }
}

{
  "name": "p-map-iterable-sample",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "p-map": "7.1.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify p-map.pMapIterable in pkg:npm/p-map@7.1.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/p-map@7.1.1"
  ],
  "symbols": [
    "p-map.pMapIterable"
  ]
}

import { pMapIterable, pMapSkip, pMapStop } from 'p-map';

export async function collectMappedIterable(input, mapper, options) {
  const results = [];
  for await (const item of pMapIterable(input, mapper, options)) {
    results.push(item);
  }
  return results;
}

export { pMapIterable, pMapSkip, pMapStop };

import assert from 'node:assert/strict';
import { setTimeout as delay } from 'node:timers/promises';
import { pMapIterable, pMapSkip, pMapStop, collectMappedIterable } from '../src/index.mjs';

// 1. Default preserveOrder: true yields mapped values in input order even when later items finish faster
{
  const delays = [30, 5, 15];
  const seenIndices = [];
  const results = await collectMappedIterable(
    ['a', 'b', 'c'],
    async (value, index) => {
      seenIndices.push(index);
      await delay(delays[index]);
      return `${value}:${index}`;
    },
    { concurrency: 2 }
  );
  assert.deepEqual(results, ['a:0', 'b:1', 'c:2']);
  assert.deepEqual(seenIndices, [0, 1, 2]);
}

// 2. preserveOrder: false yields mapped values as soon as each mapper resolves
{
  const delays = [40, 5];
  const results = await collectMappedIterable(
    ['slow', 'fast'],
    async (value, index) => {
      await delay(delays[index]);
      return value;
    },
    { concurrency: 2, preserveOrder: false }
  );
  assert.deepEqual(results, ['fast', 'slow']);
}

// 3. pMapSkip omits skipped elements and pMapStop ends iteration at the stop position
{
  let closed = false;
  async function* source() {
    try {
      yield 1;
      yield 2;
      yield 3;
      yield 4;
      yield 5;
    } finally {
      closed = true;
    }
  }

  const results = await collectMappedIterable(
    source(),
    async (value) => {
      if (value === 2) {
        return pMapSkip;
      }
      if (value === 4) {
        return pMapStop;
      }
      return value * 10;
    },
    { concurrency: 1, backpressure: 2 }
  );
  assert.deepEqual(results, [10, 30]);
  assert.equal(closed, true);
}

// 4. Option validation throws TypeError synchronously when backpressure < concurrency or concurrency < 1
{
  assert.throws(
    () => pMapIterable([1, 2], async (x) => x, { concurrency: 0 }),
    TypeError
  );
  assert.throws(
    () => pMapIterable([1, 2], async (x) => x, { concurrency: 3, backpressure: 2 }),
    TypeError
  );
}