Port opennextjs/opennextjs-aws#1118 as a test

Author: conico974

packages/open-next/src/core/routing/i18n/index.ts

@@ -4,7 +4,7 @@ import type { InternalEvent, InternalResult } from "@/types/open-next";
 import { emptyReadableStream } from "@/utils/stream.js";
 
 import { debug } from "../../../adapters/logger.js";
-import { constructNextUrl } from "../util.js";
+import { constructNextUrl, convertToQueryString } from "../util.js";
 
 import { acceptLanguage } from "./accept-header";
 
@@ -139,11 +139,16 @@ export function handleLocaleRedirect(internalEvent: InternalEvent): false | Inte
 	const defaultLocale = domainLocale?.defaultLocale ?? i18n.defaultLocale;
 
 	if (detectedLocale.toLowerCase() !== defaultLocale.toLowerCase()) {
+		const nextUrl = constructNextUrl(
+			internalEvent.url,
+			`/${detectedLocale}${NextConfig.trailingSlash ? "/" : ""}`
+		);
+		const queryString = convertToQueryString(internalEvent.query);
 		return {
 			type: "core",
 			statusCode: 307,
 			headers: {
-				Location: constructNextUrl(internalEvent.url, `/${detectedLocale}`),
+				Location: `${nextUrl}${queryString}`,
 			},
 			body: emptyReadableStream(),
 			isBase64Encoded: false,

packages/tests-unit/tests/core/routing/i18n.test.ts

@@ -11,6 +11,7 @@ vi.mock("@opennextjs/aws/adapters/config/index.js", () => {
 				defaultLocale: "en",
 				locales: ["en", "fr"],
 			},
+			trailingSlash: undefined,
 		},
 	};
 });
@@ -225,6 +226,46 @@ describe("handleLocaleRedirect", () => {
 		expect(result).toBe(false);
 	});
 
+	it("should redirect to the localized path with a query parameter", () => {
+		const event = createEvent({
+			url: "http://localhost?foo=bar",
+			headers: {
+				"accept-language": "fr",
+			},
+		});
+
+		const result = handleLocaleRedirect(event);
+
+		expect(result).toMatchObject({
+			statusCode: 307,
+			headers: {
+				Location: "http://localhost/fr?foo=bar",
+			},
+		});
+	});
+
+	it("should redirect to the localized path with a query parameter when trailingSlash is true", () => {
+		const trailingSlashSpy = vi.spyOn(NextConfig, "trailingSlash", "get").mockReturnValue(true);
+
+		const event = createEvent({
+			url: "http://localhost?foo=bar",
+			headers: {
+				"accept-language": "fr",
+			},
+		});
+
+		const result = handleLocaleRedirect(event);
+
+		expect(result).toMatchObject({
+			statusCode: 307,
+			headers: {
+				Location: "http://localhost/fr/?foo=bar",
+			},
+		});
+
+		trailingSlashSpy.mockRestore();
+	});
+
 	describe("using domain", () => {
 		it("should redirect to the preferred domain if the domain is different", () => {
 			vi.spyOn(NextConfig, "i18n", "get").mockReturnValue({