Replace PATH_KEY with pathKey(), delete fixtureEnv

The original motivation was the loss of branch coverage from the
PATH_KEY initialization expression only ever following one branch. But
it also made the getPath.test.js tests more self-documenting.

The same goes for hoisting the logic of the former fixtureEnv() helper
into the getPath test fixture itself. Also, today I learned two things:

1. Forward slashes are legal Windows path separators, per:
   https://stackoverflow.com/a/63251716

2. Node's path.join() will convert any forward slashes in any of its
   arguments to backslashes on Windows:

   ```pwsh
   > node -e "console.log(path.join('foo/bar\baz/quux', 'xyzzy/plugh'))"
   foo\baaz\quux\xyzzy\plugh
   ```

Hence the replacement of path.join(...) with plain 'usr/local/bin', etc.

lib/index.js

@@ -54,33 +54,35 @@ export async function runJsdoc(argv, env, platform) {
 }
 
 /**
- * The key for the command search path within process.env.
- *
- * On every system other than Windows, this will be "PATH". On Windows, this
- * will be "Path".
+ * Determines the key for the command search path within process.env.
+ * @param {string} platform - the process.platform string
+ * @returns {string} - On every platform other than 'win32', this will be "PATH"
+ * On 'win32', this will be "Path".
  */
-export const PATH_KEY = process.platform !== 'win32' ? 'PATH' : 'Path'
+export const pathKey = (platform) => platform !== 'win32' ? 'PATH' : 'Path'
 
 /**
  * Returns the full path to the specified command
- * @param {string} cmdName - command to find in env[PATH_KEY]
+ * @param {string} cmdName - command to find in env[pathKey(platform)]
  * @param {object} env - environment variables, presumably process.env
  * @param {string} platform - the process.platform string
  * @returns {Promise<string>} - path to the command
  */
 export async function getPath(cmdName, env, platform) {
-  for (const p of env[PATH_KEY].split(path.delimiter)) {
-    // pnpm will install both the original script and versions ending with .CMD
-    // and .ps1. We'll just default to .CMD.
-    const extension = (platform === 'win32') ? '.CMD' : ''
-    const candidate = path.join(p, cmdName) + extension
+  const pk = pathKey(platform)
+
+  // pnpm will install both the original script and versions ending with .CMD
+  // and .ps1. We'll just default to .CMD.
+  if (platform === 'win32') cmdName += '.CMD'
 
+  for (const p of env[pk].split(path.delimiter)) {
     try {
+      const candidate = path.join(p, cmdName)
       await access(candidate)
       return candidate
     } catch { /* try next candidate */ }
   }
-  return Promise.reject(`${cmdName} not found in ${PATH_KEY}`)
+  return Promise.reject(`${cmdName} not found in ${pk}`)
 }
 
 /**

test/fixtures/index.js

@@ -4,7 +4,6 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import path from 'node:path'
 import { fileURLToPath } from 'node:url'
 
 /**
@@ -15,27 +14,3 @@ import { fileURLToPath } from 'node:url'
 export function fixturePath(fixtureName) {
   return fileURLToPath(new URL(fixtureName, import.meta.url))
 }
-
-/**
- * A fake environment variable object
- * @typedef {object} FakeEnv
- * @property {string} PATH - platform-correct PATH variable
- */
-
-/**
- * Returns an environment object containing PATH set for the test fixture.
- *
- * The PATH will always contain ['usr/local/bin', 'usr/bin', 'bin'] relative to
- * the fixture root. It will be constructed using the Node.js path module to
- * ensure it's native to the host platform.
- * @param {string} fixtureName - test fixture name
- * @returns {FakeEnv} - a fake environment for the specified test fixture
- */
-export function fixtureEnv(fixtureName) {
-  const root = fixturePath(fixtureName)
-  const paths = [
-    path.join('usr', 'local', 'bin'), path.join('usr', 'bin'), 'bin'
-  ]
-  const pathKey = process.platform !== 'win32' ? 'PATH' : 'Path'
-  return {[pathKey]: paths.map(p => path.join(root, p)).join(path.delimiter)}
-}

test/getPath.test.js

@@ -5,26 +5,36 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import { getPath, PATH_KEY } from '../lib'
-import { fixturePath, fixtureEnv } from './fixtures'
+import { getPath, pathKey } from '../lib'
+import { fixturePath } from './fixtures'
 import { describe, expect, test } from 'vitest'
 import path from 'node:path'
 
+const PATH_KEY = pathKey(process.platform)
+
 describe('getPath', () => {
   const root = fixturePath('getPath')
-  const env = fixtureEnv('getPath')
+  const envPath = ['usr/local/bin', 'usr/bin', 'bin']
+    .map(p => path.join(root, p))
+    .join(path.delimiter)
 
   test('finds command on POSIX system', async() => {
+    const env = {[pathKey('linux')]: envPath}
+
     await expect(getPath('testcmd', env, 'linux')).resolves
-      .toBe(path.join(root, 'bin', 'testcmd'))
+      .toBe(path.join(root, 'bin/testcmd'))
   })
 
   test('finds command on Windows system', async() => {
+    const env = {[pathKey('win32')]: envPath}
+
     await expect(getPath('testcmd', env, 'win32')).resolves
-      .toBe(path.join(root, 'usr', 'bin', 'testcmd.CMD'))
+      .toBe(path.join(root, 'usr/bin/testcmd.CMD'))
   })
 
   test('rejects when command isn\'t found', async () => {
+    const env = {[PATH_KEY]: envPath}
+
     await expect(getPath('nonexistent', env, process.platform)).rejects
       .toBe(`nonexistent not found in ${PATH_KEY}`)
   })

test/main.test.js

@@ -5,14 +5,16 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import { getPath, PATH_KEY } from '../lib'
+import { getPath, pathKey } from '../lib'
 import { fixturePath } from './fixtures'
 import DestDirHelper from './DestDirHelper'
 import { afterEach, describe, expect, test } from 'vitest'
 import { spawn } from 'node:child_process'
 import path from 'node:path'
 import { fileURLToPath } from 'node:url'
 
+const PATH_KEY = pathKey(process.platform)
+
 describe('jsdoc-cli-wrapper', () => {
   const root = fixturePath('jsdocStub')
   const destDirHelper = new DestDirHelper()

test/runJsdoc.test.js

@@ -5,12 +5,14 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/.
  */
 
-import { runJsdoc, PATH_KEY } from '../lib'
+import { runJsdoc, pathKey } from '../lib'
 import { fixturePath } from './fixtures'
 import DestDirHelper from './DestDirHelper'
 import { afterEach, beforeEach, describe, expect, test } from 'vitest'
 import path from 'node:path'
 
+const PATH_KEY = pathKey(process.platform)
+
 describe('runJsdoc', () => {
   const root = fixturePath('jsdocStub')
   const env = { [PATH_KEY]: root }