@npmcli/promise-spawn 8.0.3: promiseSpawn

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/promise-spawn@8.0.3
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40npmcli/promise-spawn@8.0.3

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:d7f346821404d0c430de0e568ec785cc561c6d4e7058124a11f3a0006dc1470e","contract":["promiseSpawn(cmd, args, opts, extra) spawns a child process and resolves with { cmd, args, code: 0, signal: null, stdout, stderr, ...extra } where stdout and stderr are trimmed strings by default","Passing { stdioString: false } in opts returns raw Buffer instances for stdout and stderr without trimming","The returned Promise exposes .stdin and .process properties referencing the underlying child process streams and handle","When the child exits with a non-zero code, the promise rejects with Error('command failed') decorated with code, signal, stdout, stderr, and extra properties"],"goal":"verify pkg:npm/%40npmcli/promise-spawn@8.0.3","kind":"HOW","packages":["pkg:npm/%40npmcli/promise-spawn@8.0.3"],"schemaVersion":1,"symbols":["promiseSpawn"]},"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/promise-spawn@8.0.3"],"schemaVersion":1,"subject":"pkg:npm/%40npmcli/promise-spawn@8.0.3","symbols":["promiseSpawn"],"verifierAdapter":"node-typescript@1"}

{
  "name": "verify-promise-spawn",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "verify-promise-spawn",
      "version": "1.0.0",
      "dependencies": {
        "@npmcli/promise-spawn": "8.0.3"
      }
    },
    "node_modules/@npmcli/promise-spawn": {
      "version": "8.0.3",
      "resolved": "https://registry.npmjs.org/@npmcli/promise-spawn/-/promise-spawn-8.0.3.tgz",
      "integrity": "sha512-Yb00SWaL4F8w+K8YGhQ55+xE4RUNdMHV43WZGsiTM92gS+lC0mGsn7I4hLug7pbao035S6bj3Y3w0cUNGLfmkg==",
      "license": "ISC",
      "dependencies": {
        "which": "^5.0.0"
      },
      "engines": {
        "node": "^18.17.0 || >=20.5.0"
      }
    },
    "node_modules/isexe": {
      "version": "3.1.5",
      "resolved": "https://registry.npmjs.org/isexe/-/isexe-3.1.5.tgz",
      "integrity": "sha512-6B3tLtFqtQS4ekarvLVMZ+X+VlvQekbe4taUkf/rhVO3d/h0M2rfARm/pXLcPEsjjMsFgrFgSrhQIxcSVrBz8w==",
      "license": "BlueOak-1.0.0",
      "engines": {
        "node": ">=18"
      }
    },
    "node_modules/which": {
      "version": "5.0.0",
      "resolved": "https://registry.npmjs.org/which/-/which-5.0.0.tgz",
      "integrity": "sha512-JEdGzHwwkrbWoGOlIHqQ5gtprKGOenpDHpxE9zVR1bWbOtYRyPPHMe9FaP6x61CmNaTThSkb0DAJte5jD+DmzQ==",
      "license": "ISC",
      "dependencies": {
        "isexe": "^3.1.1"
      },
      "bin": {
        "node-which": "bin/which.js"
      },
      "engines": {
        "node": "^18.17.0 || >=20.5.0"
      }
    }
  }
}

{
  "name": "verify-promise-spawn",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "@npmcli/promise-spawn": "8.0.3"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/%40npmcli/promise-spawn@8.0.3",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40npmcli/promise-spawn@8.0.3"
  ]
}

import assert from 'node:assert/strict'
import promiseSpawn from '@npmcli/promise-spawn'

// 1. Successful execution returns trimmed stdout/stderr strings and extra properties
const ok = await promiseSpawn(
  process.execPath,
  ['-e', 'process.stdout.write("  hello world  \\n"); process.stderr.write("  warn  \\n")'],
  {},
  { tag: 'ok-run' }
)
assert.equal(ok.code, 0)
assert.equal(ok.signal, null)
assert.equal(ok.stdout, 'hello world')
assert.equal(ok.stderr, 'warn')
assert.equal(ok.tag, 'ok-run')
assert.deepEqual(ok.args, ['-e', 'process.stdout.write("  hello world  \\n"); process.stderr.write("  warn  \\n")'])

// 2. stdioString: false returns raw Buffers without trimming
const raw = await promiseSpawn(
  process.execPath,
  ['-e', 'process.stdout.write("raw\\n")'],
  { stdioString: false }
)
assert.ok(Buffer.isBuffer(raw.stdout))
assert.equal(raw.stdout.toString('utf8'), 'raw\n')
assert.ok(Buffer.isBuffer(raw.stderr))
assert.equal(raw.stderr.length, 0)

// 3. Returned promise exposes .stdin and .process handles
const childPromise = promiseSpawn(
  process.execPath,
  ['-e', 'process.stdin.pipe(process.stdout)']
)
assert.ok(childPromise.stdin)
assert.ok(childPromise.process)
childPromise.stdin.end('piped input\n')
const piped = await childPromise
assert.equal(piped.stdout, 'piped input')

// 4. Non-zero exit code rejects with Error('command failed') decorated with result + extra
await assert.rejects(
  () => promiseSpawn(
    process.execPath,
    ['-e', 'process.stderr.write("boom\\n"); process.exit(3)'],
    {},
    { context: 'fail-test' }
  ),
  (err) => {
    assert.equal(err.message, 'command failed')
    assert.equal(err.code, 3)
    assert.equal(err.stderr, 'boom')
    assert.equal(err.context, 'fail-test')
    return true
  }
)