concat-map 0.0.1: concat-map

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 pkg:npm/concat-map@0.0.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/concat-map@0.0.1
Demonstrate these symbols/APIs:
  - concat-map

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:a799f67eb470c6003921cf621096c6562a31e0f1de5b6da457c1d3009e095034","contract":["concatMap(xs, fn) maps fn over xs and concatenates returned arrays into a single flattened array","concatMap(xs, fn) appends non-array return values directly to the result array","concatMap(xs, fn) excludes items when fn returns an empty array","concatMap(xs, fn) passes both the element value and element index to fn"],"goal":"verify pkg:npm/concat-map@0.0.1","kind":"HOW","packages":["pkg:npm/concat-map@0.0.1"],"schemaVersion":1,"symbols":["concat-map"]},"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/concat-map@0.0.1"],"schemaVersion":1,"subject":"pkg:npm/concat-map@0.0.1","symbols":["concat-map"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-concat-map",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-concat-map",
      "version": "1.0.0",
      "dependencies": {
        "concat-map": "0.0.1"
      }
    },
    "node_modules/concat-map": {
      "version": "0.0.1",
      "resolved": "https://registry.npmjs.org/concat-map/-/concat-map-0.0.1.tgz",
      "integrity": "sha512-/Srv4dswyQNBfohGpz9o6Yb3Gz3SrUDqBH5rTuhGR7ahtlbYKnVxw2bCFMRljaA7EXHaXZ8wsHdodFvbkhKmqg==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-concat-map",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "dependencies": {
    "concat-map": "0.0.1"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/concat-map@0.0.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/concat-map@0.0.1"
  ],
  "symbols": [
    "concat-map"
  ]
}

import assert from 'node:assert/strict';
import concatMap from 'concat-map';

// 1. Mapping each element to an array flattens one level into the result
const xs = [1, 2, 3];
const result1 = concatMap(xs, (x) => [x, x * 10]);
assert.deepStrictEqual(result1, [1, 10, 2, 20, 3, 30]);

// 2. Mapping returning non-array elements appends them directly
const result2 = concatMap(['a', 'b', 'c'], (x, i) => (i % 2 === 0 ? [x, x.toUpperCase()] : x));
assert.deepStrictEqual(result2, ['a', 'A', 'b', 'c', 'C']);

// 3. Mapping returning empty array filters out elements
const result3 = concatMap([1, 2, 3, 4], (x) => (x % 2 === 0 ? [x * 2] : []));
assert.deepStrictEqual(result3, [4, 8]);

// 4. Passes element and index to the mapper function
const indices = [];
const mapped = concatMap(['foo', 'bar'], (val, idx) => {
  indices.push(idx);
  return [val + idx];
});
assert.deepStrictEqual(indices, [0, 1]);
assert.deepStrictEqual(mapped, ['foo0', 'bar1']);

// 5. Handles empty input array
const resultEmpty = concatMap([], (x) => [x]);
assert.deepStrictEqual(resultEmpty, []);