fix: resolve Windows worker PATH names case-insensitively

lib/index.js

@@ -15,8 +15,20 @@ const rRel = new RegExp(`^\\.${rSlash.source}`)
 const getNotFoundError = (cmd) =>
   Object.assign(new Error(`not found: ${cmd}`), { code: 'ENOENT' })
 
+const getPathEnv = () => {
+  if (!isWindows || process.env.PATH !== undefined) {
+    return process.env.PATH
+  }
+  // Worker environments are case-sensitive even on Windows.
+  for (const key of Object.keys(process.env)) {
+    if (key.toLowerCase() === 'path') {
+      return process.env[key]
+    }
+  }
+}
+
 const getPathInfo = (cmd, {
-  path: optPath = process.env.PATH,
+  path: optPath = getPathEnv(),
   pathExt: optPathExt = process.env.PATHEXT,
   delimiter: optDelimiter = delimiter,
 }) => {

test/path-env.js

@@ -0,0 +1,105 @@
+const t = require('tap')
+const { join } = require('path')
+const { Worker } = require('worker_threads')
+const { once } = require('events')
+
+const nativeWindows = process.platform === 'win32'
+const whichFile = require.resolve('..')
+
+const loadWhich = (t, platform, env, executable) => {
+  const originalEnv = process.env
+  const originalPlatform = Object.getOwnPropertyDescriptor(process, 'platform')
+  process.env = env
+  Object.defineProperty(process, 'platform', { ...originalPlatform, value: platform })
+  t.teardown(() => {
+    process.env = originalEnv
+    Object.defineProperty(process, 'platform', originalPlatform)
+  })
+  const matches = p => p === executable
+  return t.mock('..', { isexe: { isexe: async p => matches(p), sync: matches } })
+}
+
+for (const key of ['Path', 'path', 'pAtH']) {
+  t.test(`Windows resolves a command from ${key} when PATH is absent`, async t => {
+    const dir = t.testdir({ 'fixture.cmd': '@echo fixture\n' })
+    const file = join(dir, 'fixture.cmd')
+    const which = loadWhich(t, 'win32', { OTHER: 'fixture', [key]: dir, PATHEXT: '.CMD' }, file)
+    t.equal(await which('fixture'), file, 'async')
+    t.equal(which.sync('fixture'), file, 'sync')
+  })
+}
+
+t.test('Windows preserves an explicitly present PATH, including an empty value', async t => {
+  const dir = t.testdir({ 'fixture.cmd': '@echo fixture\n' })
+  const file = join(dir, 'fixture.cmd')
+  const env = { PATH: dir, Path: 'ignored', PATHEXT: '.CMD' }
+  const which = loadWhich(t, 'win32', env, file)
+  t.equal(await which('fixture'), file)
+  t.equal(which.sync('fixture'), file)
+  env.PATH = ''
+  env.Path = dir
+  t.equal(await which('fixture', { nothrow: true }), null, 'empty PATH does not fall back')
+  t.equal(which.sync('fixture', { nothrow: true }), null)
+})
+
+t.test('an explicit path option overrides the Windows environment', async t => {
+  const dir = t.testdir({ 'fixture.cmd': '@echo fixture\n' })
+  const file = join(dir, 'fixture.cmd')
+  const which = loadWhich(t, 'win32', { Path: 'ignored', PATHEXT: '.CMD' }, file)
+  t.equal(await which('fixture', { path: dir }), file)
+  t.equal(which.sync('fixture', { path: dir }), file)
+  t.equal(await which('fixture', { path: '', nothrow: true }), null)
+  t.equal(which.sync('fixture', { path: '', nothrow: true }), null)
+})
+
+t.test('POSIX ignores differently cased environment names', async t => {
+  const dir = t.testdir({ fixture: 'fixture\n' })
+  const file = join(dir, 'fixture')
+  const env = { Path: dir, path: dir }
+  const which = loadWhich(t, 'linux', env, file)
+  t.equal(await which('fixture', { nothrow: true }), null)
+  t.equal(which.sync('fixture', { nothrow: true }), null)
+  env.PATH = dir
+  t.equal(await which('fixture'), file, 'uppercase PATH still works')
+  t.equal(which.sync('fixture'), file)
+})
+
+t.test('Windows with no PATH spelling retains not-found behavior', async t => {
+  const which = loadWhich(t, 'win32', { OTHER: 'fixture', PATHEXT: '.CMD' }, '')
+  await t.rejects(which('fixture'), { code: 'ENOENT' })
+  t.throws(() => which.sync('fixture'), { code: 'ENOENT' })
+})
+
+t.test('the Windows fallback reads the current environment on each call', async t => {
+  const dir = t.testdir({ 'fixture.cmd': '@echo fixture\n' })
+  const file = join(dir, 'fixture.cmd')
+  const env = { Path: dir, PATHEXT: '.CMD' }
+  const which = loadWhich(t, 'win32', env, file)
+  t.equal(await which('fixture'), file)
+  delete env.Path
+  env.pAtH = 'not-the-fixture-directory'
+  t.equal(which.sync('fixture', { nothrow: true }), null)
+  env.pAtH = dir
+  t.equal(which.sync('fixture'), file)
+})
+
+t.test('a real Windows worker resolves Path without inheriting the parent environment', {
+  skip: !nativeWindows && 'requires Windows worker environment semantics',
+}, async t => {
+  const dir = t.testdir({ 'fixture.cmd': '@echo fixture\n' })
+  const file = join(dir, 'fixture.cmd')
+  const worker = new Worker(`
+    const { parentPort } = require('worker_threads')
+    const which = require(${JSON.stringify(whichFile)})
+    ;(async () => {
+      parentPort.postMessage({
+        upperPathAbsent: process.env.PATH === undefined,
+        async: await which('fixture.cmd', { nothrow: true }),
+        sync: which.sync('fixture.cmd', { nothrow: true }),
+      })
+    })().catch(error => { throw error })
+  `, { eval: true, env: { Path: dir, PATHEXT: '.CMD' } })
+  t.teardown(() => worker.terminate())
+  const [result] = await once(worker, 'message')
+  t.same(result, { upperPathAbsent: true, async: file, sync: file })
+})