Support i18n localeDetection with value false

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

@@ -21,6 +21,10 @@ function getLocaleFromCookie(cookies: Record<string, string>) {
 }
 
 function detectLocale(internalEvent: InternalEvent, i18n: i18nConfig): string {
+  if (i18n.localeDetection === false) {
+    return i18n.defaultLocale;
+  }
+
   const cookiesLocale = getLocaleFromCookie(internalEvent.cookies);
   const preferredLocale = acceptLanguage(
     internalEvent.headers["accept-language"],

packages/open-next/src/types/next-types.ts

@@ -64,6 +64,7 @@ export type Header = {
 export interface i18nConfig {
   locales: string[];
   defaultLocale: string;
+  localeDetection?: false;
 }
 export interface NextConfig {
   basePath?: string;

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

@@ -0,0 +1,144 @@
+import { NextConfig } from "@opennextjs/aws/adapters/config/index.js";
+import { localizePath } from "@opennextjs/aws/core/routing/i18n/index.js";
+import { convertFromQueryString } from "@opennextjs/aws/core/routing/util.js";
+import type { InternalEvent } from "@opennextjs/aws/types/open-next.js";
+import { vi } from "vitest";
+
+vi.mock("@opennextjs/aws/adapters/config/index.js", () => {
+  return {
+    NextConfig: {
+      i18n: {
+        defaultLocale: "en",
+        locales: ["en", "fr"],
+      },
+    },
+  };
+});
+
+vi.mock("@opennextjs/aws/core/routing/i18n/accept-header.js", () => ({
+  acceptLanguage: (header: string, _?: string[]) => (header ? "fr" : undefined),
+}));
+
+type PartialEvent = Partial<
+  Omit<InternalEvent, "body" | "rawPath" | "query">
+> & { body?: string };
+
+function createEvent(event: PartialEvent): InternalEvent {
+  const [rawPath, qs] = (event.url ?? "/").split("?", 2);
+  return {
+    type: "core",
+    method: event.method ?? "GET",
+    rawPath,
+    url: event.url ?? "/",
+    body: Buffer.from(event.body ?? ""),
+    headers: event.headers ?? {},
+    query: convertFromQueryString(qs ?? ""),
+    cookies: event.cookies ?? {},
+    remoteAddress: event.remoteAddress ?? "::1",
+  };
+}
+
+beforeEach(() => {
+  vi.resetAllMocks();
+});
+
+describe("localizePath", () => {
+  it("should return raw path if no i18n config is set", () => {
+    const i18nSpy = vi
+      .spyOn(NextConfig, "i18n", "get")
+      .mockReturnValue(undefined);
+
+    const event = createEvent({
+      url: "/foo",
+    });
+
+    const result = localizePath(event);
+
+    expect(result).toEqual("/foo");
+
+    i18nSpy.mockRestore();
+  });
+
+  it("should return default locale localized if localeDetection is set to false", () => {
+    const i18nSpy = vi.spyOn(NextConfig, "i18n", "get").mockReturnValue({
+      defaultLocale: "en",
+      locales: ["en", "fr"],
+      localeDetection: false,
+    });
+
+    const event = createEvent({
+      url: "/foo",
+      headers: {
+        "accept-language": "fr",
+      },
+      cookies: {
+        NEXT_LOCALE: "fr",
+      },
+    });
+
+    const result = localizePath(event);
+
+    expect(result).toEqual("/en/foo");
+
+    i18nSpy.mockRestore();
+  });
+
+  it("should return the same path if the path is already localized", () => {
+    const event = createEvent({
+      url: "/fr/foo",
+    });
+
+    const result = localizePath(event);
+
+    expect(result).toEqual("/fr/foo");
+  });
+
+  it("should get locale from cookies if NEXT_LOCALE cookie is set to a valid locale", () => {
+    const event = createEvent({
+      url: "/foo",
+      cookies: {
+        NEXT_LOCALE: "fr",
+      },
+    });
+
+    const result = localizePath(event);
+
+    expect(result).toEqual("/fr/foo");
+  });
+
+  it("should fallback on default locale if NEXT_LOCALE cookie is set to an invalid locale", () => {
+    const event = createEvent({
+      url: "/foo",
+      cookies: {
+        NEXT_LOCALE: "pt",
+      },
+    });
+
+    const result = localizePath(event);
+
+    expect(result).toEqual("/en/foo");
+  });
+
+  it("should use accept-language header if no cookie are present", () => {
+    const event = createEvent({
+      url: "/foo",
+      headers: {
+        "accept-language": "fr",
+      },
+    });
+
+    const result = localizePath(event);
+
+    expect(result).toEqual("/fr/foo");
+  });
+
+  it("should fallback to default locale if no cookie or header are set", () => {
+    const event = createEvent({
+      url: "/foo",
+    });
+
+    const result = localizePath(event);
+
+    expect(result).toEqual("/en/foo");
+  });
+});