Ask git the root of the repo instead of (wrongly) looking for a .git folder

Author: Septh

source/index.ts

@@ -1,5 +1,6 @@
 import path from 'node:path'
 import fs from 'node:fs/promises'
+import cp from 'node:child_process'
 import { createRequire, isBuiltin } from 'node:module'
 import type { Plugin } from 'rollup'
 
@@ -98,7 +99,7 @@ const { name, version } = createRequire(import.meta.url)('#package.json') as Pac
 // Files that mark the root of a monorepo
 const workspaceRootFiles = [
     'pnpm-workspace.yaml',  // pnpm
-    'lerna.json',           // Lerna
+    'lerna.json',           // Lerna / Lerna Light
     // Note: is there any interest in the following?
     // 'workspace.jsonc',      // Bit
     // 'nx.json',              // Nx
@@ -126,7 +127,7 @@ const isString = (str: unknown): str is string =>
  * A Rollup/Vite plugin that automatically declares NodeJS built-in modules,
  * and optionally npm dependencies, as 'external'.
  */
-function nodeExternals(options: ExternalsOptions = {}): Plugin {
+async function nodeExternals(options: ExternalsOptions = {}): Promise<Plugin> {
 
     const config: Config = { ...defaults, ...options }
 
@@ -136,6 +137,13 @@ function nodeExternals(options: ExternalsOptions = {}): Plugin {
     const isIncluded = (id: string) => include.length > 0 && include.some(rx => rx.test(id)),
           isExcluded = (id: string) => exclude.length > 0 && exclude.some(rx => rx.test(id))
 
+    // Determine the root of the git repository, if any.
+    const gitRepository = await new Promise<string | null>(resolve => {
+        cp.execFile('git', [ 'rev-parse', '--show-toplevel' ], (error, stdout) => {
+            return resolve(error ? null : path.normalize(stdout.trim()))
+        })
+    })
+
     return {
         name: name.replace(/^rollup-plugin-/, ''),
         version,
@@ -165,29 +173,24 @@ function nodeExternals(options: ExternalsOptions = {}): Plugin {
                 .concat(config.packagePath)
                 .filter(isString)
                 .map(packagePath => path.resolve(packagePath))
+
             if (packagePaths.length === 0) {
-                search: for (
-                    let current = process.cwd(), previous: string | undefined = undefined;
-                    previous !== current;
-                    previous = current, current = path.dirname(current)
-                ) {
+                search:
+                for (let current = process.cwd(), previous: string | undefined = undefined; previous !== current; previous = current, current = path.dirname(current)) {
+
                     // Gather package.json files.
                     let name = path.join(current, 'package.json')
                     let stat = await fs.stat(name).catch(() => null)
                     if (stat?.isFile())
                         packagePaths.push(name)
 
                     // Break early if we are at the root of a git repo.
-                    name = path.join(current, '.git')
-                    stat = await fs.stat(name).catch(() => null)
-                    if (stat?.isDirectory())
+                    if (current === gitRepository)
                         break
 
                     // Break early is there is a known workspace root file.
                     for (const file of workspaceRootFiles) {
-                        name = path.join(current, file)
-                        stat = await fs.stat(name).catch(() => null)
-                        if (stat?.isFile())
+                        if (await fs.stat(path.join(current, file)).then(stat => stat.isFile()).catch(() => false))
                             break search
                     }
                 }

test/_common.ts

@@ -54,7 +54,7 @@ class MockPluginContext {
 }
 
 export async function initPlugin(options: ExternalsOptions = {}) {
-    const plugin = nodeExternals(options)
+    const plugin = await nodeExternals(options)
     const context = new MockPluginContext(plugin)
     await context.buildStart()
     return context

test/monorepo.test.ts

@@ -1,13 +1,26 @@
+import { promisify } from 'node:util'
+import cp from 'node:child_process'
 import fs from 'node:fs/promises'
 import test from 'ava'
 import { initPlugin, fixture } from './_common.ts'
 
-// These two tests need to be run in sequence
+// The two tests in this file need to be run in sequence so one does not interfere with the other
+
 test.serial('git monorepo usage', async t => {
-    await fs.mkdir(fixture('01_monorepo/.git'), { recursive: true })
-    process.chdir(fixture('01_monorepo/one'))
+
+    t.log('Creating temporary git repo...')
+    process.chdir(fixture('01_monorepo'))
+    const execFile = promisify(cp.execFile)
+    await execFile('git', [ 'init' ] ).catch(() => {})
+
+    t.teardown(async () => {
+        t.log('Removing temporary git repo...')
+        process.chdir(fixture('01_monorepo'))
+        await fs.rm('.git', { recursive: true, force: true })
+    })
 
     // Should gather dependencies up to ./test/fixtures/01_monorepo
+    process.chdir(fixture('01_monorepo/one'))
     const context = await initPlugin()
 
     // Should be external
@@ -28,10 +41,9 @@ test.serial('git monorepo usage', async t => {
 })
 
 test.serial('non-git monorepo usage', async t => {
-    await fs.rmdir(fixture('01_monorepo/.git'))
-    process.chdir(fixture('01_monorepo/one'))
 
-    // Should gather dependencies up to . !
+    // Should gather dependencies up to / !
+    process.chdir(fixture('01_monorepo/one'))
     const context = await initPlugin()
 
     // Should be external