fix: sort discovered locales for deterministic generator output

packages/generator/test/get-all-locales.test.ts

@@ -0,0 +1,44 @@
+import { suite } from 'uvu'
+import * as assert from 'uvu/assert'
+import { getAllLocales, type FileSystemUtil } from '../../shared/src/file.utils.mjs'
+
+const test = suite('getAllLocales')
+
+type Dirent = { name: string; isDirectory: () => boolean }
+
+const folder = (name: string): Dirent => ({ name, isDirectory: () => true })
+const file = (name: string): Dirent => ({ name, isDirectory: () => false })
+
+const ROOT = './i18n'
+
+// the order in which the filesystem returns directory entries is not guaranteed
+// to be stable across platforms or runs, so `getAllLocales` must sort the result
+// to produce a deterministic output
+const createFileSystem = (rootEntries: Dirent[]): FileSystemUtil => ({
+	readFile: async () => '',
+	readdir: async (path) => (String(path) === ROOT ? rootEntries : [file('index.ts')]),
+})
+
+test('returns the discovered locales sorted alphabetically', async () => {
+	const fs = createFileSystem([folder('sk'), folder('cs'), folder('en')])
+
+	assert.equal(await getAllLocales(fs, ROOT, 'TypeScript'), ['cs', 'en', 'sk'])
+})
+
+test('sorts locales independently of the filesystem order', async () => {
+	const ascending = createFileSystem([folder('cs'), folder('en'), folder('sk')])
+	const descending = createFileSystem([folder('sk'), folder('en'), folder('cs')])
+
+	assert.equal(await getAllLocales(ascending, ROOT, 'TypeScript'), await getAllLocales(descending, ROOT, 'TypeScript'))
+})
+
+test('also sorts when looking for JavaScript locale files', async () => {
+	const fs: FileSystemUtil = {
+		readFile: async () => '',
+		readdir: async (path) => (String(path) === ROOT ? [folder('sk'), folder('cs')] : [file('index.js')]),
+	}
+
+	assert.equal(await getAllLocales(fs, ROOT, 'JavaScript'), ['cs', 'sk'])
+})
+
+test.run()

packages/shared/src/file.utils.mts

@@ -38,5 +38,8 @@ export const getAllLocales = async (
 	const fileEnding = outputFormat === 'JavaScript' ? '.js' : '.ts'
 	const files = await getFiles(fs, path, 1)
 
-	return files.filter(({ folder, name }) => folder && name === `index${fileEnding}`).map(({ folder }) => folder)
+	return files
+		.filter(({ folder, name }) => folder && name === `index${fileEnding}`)
+		.map(({ folder }) => folder)
+		.sort()
 }