marriage/proxy.test.ts

import { NextRequest } from "next/server";
import { describe, expect, it } from "vitest";
import { config, proxy } from "./proxy";

function request(path: string, cookie?: string, acceptLanguage?: string) {
  return new NextRequest(`https://example.test${path}`, {
    headers: {
      ...(cookie ? { cookie } : {}),
      ...(acceptLanguage ? { "accept-language": acceptLanguage } : {}),
    },
  });
}

describe("locale proxy", () => {
  it("redirects a localized path when the authoritative cookie differs", () => {
    const response = proxy(request("/en/questions-list", "HABIB_LANGUAGE=fa"));
    expect(response.status).toBe(307);
    expect(response.headers.get("location")).toBe(
      "https://example.test/fa/questions-list",
    );
  });

  it("passes the path locale to the root layout", () => {
    const response = proxy(request("/fa/questions-list", "HABIB_LANGUAGE=fa"));
    expect(response.status).toBe(200);
    expect(response.headers.get("x-middleware-request-x-habib-locale")).toBe(
      "fa",
    );
  });

  it("excludes health checks from locale routing", () => {
    expect(config.matcher[0]).toContain("healthz");
  });

  it("falls back to the first supported accept-language entry", () => {
    const response = proxy(
      request("/questions-list", undefined, "fa-IR, fa;q=0.9, en;q=0.8"),
    );
    expect(response.status).toBe(307);
    expect(response.headers.get("location")).toBe(
      "https://example.test/fa/questions-list",
    );
  });

  it("normalizes region subtags in accept-language", () => {
    const response = proxy(
      request("/questions-list", undefined, "en-US, en;q=0.9"),
    );
    expect(response.status).toBe(307);
    expect(response.headers.get("location")).toBe(
      "https://example.test/en/questions-list",
    );
  });

  it("skips wildcard and unsupported accept-language entries", () => {
    const response = proxy(request("/questions-list", undefined, "*, und"));
    expect(response.status).toBe(307);
    expect(response.headers.get("location")).toBe(
      "https://example.test/en/questions-list",
    );
  });

  it("keeps the cookie authoritative over accept-language", () => {
    const response = proxy(
      request("/en/questions-list", "HABIB_LANGUAGE=fa", "en-US, en;q=0.9"),
    );
    expect(response.status).toBe(307);
    expect(response.headers.get("location")).toBe(
      "https://example.test/fa/questions-list",
    );
  });
});