fix: locale handling for logger (withastro#3391)

* fix(withastro#3309): use system default locale

* fix(withastro#3309): use system default locale in create-astro

* test: add locale regression tests

* test: add i18n regression test

src/core/logger/core.ts

@@ -14,18 +14,16 @@ export interface LogOptions {
 	level: LoggerLevel;
 }
 
-function getLoggerLocale(): string {
-	const defaultLocale = 'en-US';
-	if (process.env.LANG) {
-		const extractedLocale = process.env.LANG.split('.')[0].replace(/_/g, '-');
-		// Check if language code is atleast two characters long (ie. en, es).
-		// NOTE: if "c" locale is encountered, the default locale will be returned.
-		if (extractedLocale.length < 2) return defaultLocale;
-		else return extractedLocale.substring(0, 5);
-	} else return defaultLocale;
-}
-
-export const dateTimeFormat = new Intl.DateTimeFormat(getLoggerLocale(), {
+// Hey, locales are pretty complicated! Be careful modifying this logic...
+// If we throw at the top-level, international users can't use Astro.
+// 
+// Using `[]` sets the default locale properly from the system!
+// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat/DateTimeFormat#parameters
+// 
+// Here be the dragons we've slain:
+// https://github.com/withastro/astro/issues/2625
+// https://github.com/withastro/astro/issues/3309
+export const dateTimeFormat = new Intl.DateTimeFormat([], {
 	hour: '2-digit',
 	minute: '2-digit',
 	second: '2-digit',

test/cli.test.js

@@ -110,3 +110,21 @@ describe('astro cli', () => {
 		});
 	});
 });
+
+describe('astro cli i18n', () => {
+	const LOCALES = ['en_US', 'sv_SE', 'es_419.UTF-8', 'es_ES@euro', 'C'];
+	LOCALES.forEach((locale) => {
+		it(`astro does NOT throw on "${locale}" locales`, async () => {
+			const projectRootURL = new URL('./fixtures/astro-basic/', import.meta.url);
+			let error = null;
+			try {
+				const proc = cli('dev', '--root', fileURLToPath(projectRootURL), { env: { LANG: locale }});
+				await parseCliDevStart(proc)
+			} catch (e) {
+				console.log(e);
+				error = e.message;
+			}
+			expect(error).to.be.null;
+		});
+	})
+})