@npmcli/fs 4.0.0: cp, moveFile, readdirScoped

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/%40npmcli/fs@4.0.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40npmcli/fs@4.0.0

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:e713a01ed3ce468554d155d29730d9e2926ef4439fd2206591ddb839b276fdca","contract":["withTempDir(root, fn, { tmpPrefix }) creates a temporary directory prefixed with tmpPrefix, passes its path to fn, returns the resolved value of fn, and removes the temporary directory afterwards","readdirScoped(dir) lists regular entries at the top level and expands @scope/* directories into @scope/pkg relative paths","cp(src, dest) copies a file from src to dest","moveFile(source, destination, options) moves a file creating parent directories and rejects when options.overwrite is false and destination exists"],"goal":"verify pkg:npm/%40npmcli/fs@4.0.0","kind":"HOW","packages":["pkg:npm/%40npmcli/fs@4.0.0"],"schemaVersion":1,"symbols":["cp","moveFile","readdirScoped","withTempDir"]},"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/%40npmcli/fs@4.0.0"],"schemaVersion":1,"subject":"pkg:npm/%40npmcli/fs@4.0.0","symbols":["cp","moveFile","readdirScoped","withTempDir"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample",
      "version": "1.0.0",
      "dependencies": {
        "@npmcli/fs": "4.0.0"
      }
    },
    "node_modules/@npmcli/fs": {
      "version": "4.0.0",
      "resolved": "https://registry.npmjs.org/@npmcli/fs/-/fs-4.0.0.tgz",
      "integrity": "sha512-/xGlezI6xfGO9NwuJlnwz/K14qD1kCSAGtacBHnGzeAIuJGazcp45KP5NuyARXoKb7cwulAGWVsbeSxdG/cb0Q==",
      "license": "ISC",
      "dependencies": {
        "semver": "^7.3.5"
      },
      "engines": {
        "node": "^18.17.0 || >=20.5.0"
      }
    },
    "node_modules/semver": {
      "version": "7.8.5",
      "resolved": "https://registry.npmjs.org/semver/-/semver-7.8.5.tgz",
      "integrity": "sha512-Y7/KDsb8LjooZpwaqGyulO6DQlksgCncchHGk+sZIY4SBvUocMBEFH5Ur1fI4dV+Jvl0w6cjvucaIi40puRioA==",
      "license": "ISC",
      "bin": {
        "semver": "bin/semver.js"
      },
      "engines": {
        "node": ">=10"
      }
    }
  }
}

{
  "name": "sample",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "@npmcli/fs": "4.0.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/%40npmcli/fs@4.0.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40npmcli/fs@4.0.0"
  ]
}

import assert from 'node:assert/strict';
import fs from 'node:fs/promises';
import os from 'node:os';
import path from 'node:path';
import npmFs from '@npmcli/fs';

const { withTempDir, readdirScoped, cp, moveFile } = npmFs;

const baseRoot = path.join(os.tmpdir(), 'npmcli-fs-contract');

let capturedTempDir = '';
const returnVal = await withTempDir(
  baseRoot,
  async (tempDir) => {
    capturedTempDir = tempDir;
    assert.ok(path.basename(tempDir).startsWith('pref-'));

    // 1. Test readdirScoped
    const scopedDir = path.join(tempDir, 'modules');
    await fs.mkdir(path.join(scopedDir, '@scope', 'pkg-a'), { recursive: true });
    await fs.mkdir(path.join(scopedDir, 'pkg-b'), { recursive: true });

    const entries = await readdirScoped(scopedDir);
    assert.deepEqual(
      entries.sort(),
      [path.join('@scope', 'pkg-a'), 'pkg-b'].sort()
    );

    // 2. Test cp
    const srcFile = path.join(tempDir, 'source.txt');
    const copiedFile = path.join(tempDir, 'copied.txt');
    await fs.writeFile(srcFile, 'hello world', 'utf8');
    await cp(srcFile, copiedFile);
    assert.equal(await fs.readFile(copiedFile, 'utf8'), 'hello world');

    // 3. Test moveFile (and overwrite: false check)
    const movedFile = path.join(tempDir, 'sub', 'moved.txt');
    await moveFile(copiedFile, movedFile);
    assert.equal(await fs.readFile(movedFile, 'utf8'), 'hello world');
    await assert.rejects(fs.access(copiedFile), { code: 'ENOENT' });

    await assert.rejects(
      moveFile(srcFile, movedFile, { overwrite: false }),
      /The destination file exists/
    );

    return 'done';
  },
  { tmpPrefix: 'pref-' }
);

assert.equal(returnVal, 'done');
await assert.rejects(fs.access(capturedTempDir), { code: 'ENOENT' });
await fs.rm(baseRoot, { recursive: true, force: true });