cmd-shim 7.0.0: ifExists

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 cmd-shim.ifExists in pkg:npm/cmd-shim@7.0.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/cmd-shim@7.0.0
Demonstrate these symbols/APIs:
  - cmd-shim.ifExists

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:ae5595989d645d66f4a68dba43f3632f66ee41f15613a44dacb16f863d56722c","contract":["cmdShim.ifExists(from, to) creates executable POSIX sh (to), Windows batch (to.cmd), and PowerShell (to.ps1) shim files with mode 0o755 and resolves to [undefined, undefined, undefined] when 'from' exists","cmdShim.ifExists(from, to) resolves to undefined without creating shim files or rejecting when 'from' does not exist, whereas cmdShim(from, to) rejects with ENOENT"],"goal":"verify cmd-shim.ifExists in pkg:npm/cmd-shim@7.0.0","kind":"HOW","packages":["pkg:npm/cmd-shim@7.0.0"],"schemaVersion":1,"symbols":["cmd-shim.ifExists"]},"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/cmd-shim@7.0.0"],"schemaVersion":1,"subject":"pkg:npm/cmd-shim@7.0.0","symbols":["cmd-shim.ifExists"],"verifierAdapter":"node-typescript@1"}

{
  "name": "verify-cmd-shim-if-exists",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "verify-cmd-shim-if-exists",
      "version": "1.0.0",
      "dependencies": {
        "cmd-shim": "7.0.0"
      }
    },
    "node_modules/cmd-shim": {
      "version": "7.0.0",
      "resolved": "https://registry.npmjs.org/cmd-shim/-/cmd-shim-7.0.0.tgz",
      "integrity": "sha512-rtpaCbr164TPPh+zFdkWpCyZuKkjpAzODfaZCf/SVJZzJN+4bHQb/LP3Jzq5/+84um3XXY8r548XiWKSborwVw==",
      "license": "ISC",
      "engines": {
        "node": "^18.17.0 || >=20.5.0"
      }
    }
  }
}

{
  "name": "verify-cmd-shim-if-exists",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "cmd-shim": "7.0.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify cmd-shim.ifExists in pkg:npm/cmd-shim@7.0.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/cmd-shim@7.0.0"
  ],
  "symbols": [
    "cmd-shim.ifExists"
  ]
}

import cmdShim from 'cmd-shim'

export async function createShimIfExists(from, to) {
  return cmdShim.ifExists(from, to)
}

import assert from 'node:assert/strict'
import { mkdtemp, readFile, rm, stat, writeFile } from 'node:fs/promises'
import { tmpdir } from 'node:os'
import { join } from 'node:path'
import cmdShim from 'cmd-shim'
import { createShimIfExists } from '../src/index.mjs'

const workDir = await mkdtemp(join(tmpdir(), 'cmd-shim-contract-'))

try {
  assert.equal(typeof cmdShim.ifExists, 'function')

  // 1. Existing source script: creates sh, .cmd, and .ps1 shims with 0o755 permissions
  const existingFrom = join(workDir, 'cli.js')
  const existingTo = join(workDir, 'bin', 'my-cli')
  await writeFile(existingFrom, '#!/usr/bin/env node\nconsole.log("ok")\n', 'utf8')

  const resultExisting = await createShimIfExists(existingFrom, existingTo)
  assert.deepEqual(resultExisting, [undefined, undefined, undefined])

  const shStat = await stat(existingTo)
  const cmdStat = await stat(`${existingTo}.cmd`)
  const ps1Stat = await stat(`${existingTo}.ps1`)

  assert.equal(shStat.isFile(), true)
  assert.equal(cmdStat.isFile(), true)
  assert.equal(ps1Stat.isFile(), true)
  assert.equal(shStat.mode & 0o111, 0o111)

  const shContent = await readFile(existingTo, 'utf8')
  const cmdContent = await readFile(`${existingTo}.cmd`, 'utf8')
  const ps1Content = await readFile(`${existingTo}.ps1`, 'utf8')

  assert.match(shContent, /^#!\/bin\/sh\n/)
  assert.match(shContent, /\.\.\/cli\.js/)
  assert.match(cmdContent, /@ECHO off\r\n/)
  assert.match(ps1Content, /^#!\/usr\/bin\/env pwsh\n/)

  // 2. Missing source script: cmdShim.ifExists resolves silently without creating shims,
  //    whereas default cmdShim rejects with ENOENT.
  const missingFrom = join(workDir, 'does-not-exist.js')
  const missingTo = join(workDir, 'bin', 'missing-cli')

  const resultMissing = await cmdShim.ifExists(missingFrom, missingTo)
  assert.equal(resultMissing, undefined)

  await assert.rejects(stat(missingTo), { code: 'ENOENT' })
  await assert.rejects(stat(`${missingTo}.cmd`), { code: 'ENOENT' })
  await assert.rejects(stat(`${missingTo}.ps1`), { code: 'ENOENT' })
  await assert.rejects(cmdShim(missingFrom, missingTo), { code: 'ENOENT' })
} finally {
  await rm(workDir, { recursive: true, force: true })
}