fix(i18n): correctly compute the current locale (#12199)

* fix(i18n): correctly compute the current locale

* Update packages/astro/test/fixtures/i18n-routing-dynamic/src/pages/[language].astro

Co-authored-by: Bjorn Lu <[email protected]>

* make code more readable

* rebase

---------

Co-authored-by: Bjorn Lu <[email protected]>

.changeset/sharp-garlics-float.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes a regression in the computation of `Astro.currentLocale`

packages/astro/src/core/render-context.ts

@@ -531,13 +531,19 @@ export class RenderContext {
 				? defaultLocale
 				: undefined;
 
-		// TODO: look into why computeCurrentLocale() needs routeData.route to pass ctx.currentLocale tests,
-		// and url.pathname to pass Astro.currentLocale tests.
-		// A single call with `routeData.pathname ?? routeData.route` as the pathname still fails.
-		return (this.#currentLocale ??=
-			computeCurrentLocale(routeData.route, locales, defaultLocale) ??
-			computeCurrentLocale(url.pathname, locales, defaultLocale) ??
-			fallbackTo);
+		if (this.#currentLocale) {
+			return this.#currentLocale
+		}
+
+		let computedLocale;
+		if (routeData.pathname) {
+			computedLocale =  computeCurrentLocale(routeData.pathname, locales, defaultLocale)
+		} else {
+			computedLocale = computeCurrentLocale(url.pathname, locales, defaultLocale) 
+		}
+		this.#currentLocale = computedLocale ?? fallbackTo;
+
+		return this.#currentLocale
 	}
 
 	#preferredLocale: APIContext['preferredLocale'];

packages/astro/src/i18n/utils.ts

@@ -157,7 +157,6 @@ export function computeCurrentLocale(
 		for (const locale of locales) {
 			if (typeof locale === 'string') {
 				// we skip ta locale that isn't present in the current segment
-
 				if (!segment.includes(locale)) continue;
 				if (normalizeTheLocale(locale) === normalizeTheLocale(segment)) {
 					return locale;

packages/astro/test/fixtures/i18n-routing-dynamic/astro.config.mjs

@@ -0,0 +1,13 @@
+import { defineConfig } from "astro/config";
+
+// https://astro.build/config
+export default defineConfig({
+	i18n: {
+		defaultLocale: "ru",
+		locales: ["ru", "en"],
+		routing: {
+			prefixDefaultLocale: true,
+		},
+	},
+});
+

packages/astro/test/fixtures/i18n-routing-dynamic/package.json

@@ -0,0 +1,8 @@
+{
+  "name": "@test/i18n-routing-dynamic",
+  "version": "0.0.0",
+  "private": true,
+  "dependencies": {
+    "astro": "workspace:*"
+  }
+}

packages/astro/test/fixtures/i18n-routing-dynamic/src/pages/[language].astro

@@ -0,0 +1,11 @@
+---
+export async function getStaticPaths() {
+	return [{ params: { language: "ru" } }, { params: { language: "en" } }];
+}
+
+const { currentLocale } = Astro;
+---
+
+<div>
+	{currentLocale}
+</div>

packages/astro/test/i18n-routing.test.js

@@ -1,5 +1,5 @@
 import * as assert from 'node:assert/strict';
-import { after, before, describe, it } from 'node:test';
+import { after, afterEach, before, describe, it } from 'node:test';
 import * as cheerio from 'cheerio';
 import testAdapter from './test-adapter.js';
 import { loadFixture } from './test-utils.js';
@@ -1105,7 +1105,7 @@ describe('[SSG] i18n routing', () => {
 			});
 
 			it('should return the default locale', async () => {
-				const html = await fixture.readFile('/current-locale/index.html');
+				let html = await fixture.readFile('/current-locale/index.html');
 				assert.equal(html.includes('Current Locale: es'), true);
 			});
 
@@ -1151,6 +1151,30 @@ describe('[SSG] i18n routing', () => {
 				assert.equal(html.includes('Current Locale: pt'), true);
 			});
 		});
+
+		describe('with dynamic paths', async () => {
+			/** @type {import('./test-utils').Fixture} */
+			let fixture;
+			let devServer;
+
+			before(async () => {
+				fixture = await loadFixture({
+					root: './fixtures/i18n-routing/',
+				});
+				devServer = await fixture.startDevServer();
+			});
+
+			afterEach(async () => {
+				devServer.stop();
+			});
+
+			it('should return the correct current locale', async () => {
+				let html = await fixture.fetch('/en').then((r) => r.text());
+				assert.match(html, /en/);
+				html = await fixture.fetch('/ru').then((r) => r.text());
+				assert.match(html, /ru/);
+			});
+		});
 	});
 });
 describe('[SSR] i18n routing', () => {