feat(chat): implement external browser prompt logic and update tests

src/app/chat/__tests__/chat-screen.helpers.test.ts

@@ -1,10 +1,15 @@
-import { describe, expect, it } from "vitest";
+import { afterEach, describe, expect, it, vi } from "vitest";
 
 import {
   getInsufficientCreditsMessageLimitView,
+  shouldStartExternalBrowserPrompt,
   shouldShowMessageLimitBanner,
 } from "../chat-screen.helpers";
 
+afterEach(() => {
+  vi.unstubAllEnvs();
+});
+
 describe("getInsufficientCreditsMessageLimitView", () => {
   it("asks guests to log in for more free chats", () => {
     expect(getInsufficientCreditsMessageLimitView("guest")).toEqual({
@@ -65,3 +70,73 @@ describe("shouldShowMessageLimitBanner", () => {
     ).toBe(false);
   });
 });
+
+describe("shouldStartExternalBrowserPrompt", () => {
+  it("shows for facebook users inside an in-app browser", () => {
+    vi.stubEnv("NEXT_PUBLIC_APP_ENV", "production");
+
+    expect(
+      shouldStartExternalBrowserPrompt({
+        hasInitialized: true,
+        isLoading: false,
+        loginStatus: "facebook",
+        isInAppBrowser: true,
+      }),
+    ).toBe(true);
+  });
+
+  it.each(["guest", "notLoggedIn", "email", "google"] as const)(
+    "hides for %s users even inside an in-app browser",
+    (loginStatus) => {
+      vi.stubEnv("NEXT_PUBLIC_APP_ENV", "production");
+
+      expect(
+        shouldStartExternalBrowserPrompt({
+          hasInitialized: true,
+          isLoading: false,
+          loginStatus,
+          isInAppBrowser: true,
+        }),
+      ).toBe(false);
+    },
+  );
+
+  it("hides for facebook users in normal browsers", () => {
+    vi.stubEnv("NEXT_PUBLIC_APP_ENV", "production");
+
+    expect(
+      shouldStartExternalBrowserPrompt({
+        hasInitialized: true,
+        isLoading: false,
+        loginStatus: "facebook",
+        isInAppBrowser: false,
+      }),
+    ).toBe(false);
+  });
+
+  it("shows in development for easier testing", () => {
+    vi.stubEnv("NEXT_PUBLIC_APP_ENV", "development");
+
+    expect(
+      shouldStartExternalBrowserPrompt({
+        hasInitialized: true,
+        isLoading: false,
+        loginStatus: "guest",
+        isInAppBrowser: false,
+      }),
+    ).toBe(true);
+  });
+
+  it("waits for auth initialization", () => {
+    vi.stubEnv("NEXT_PUBLIC_APP_ENV", "production");
+
+    expect(
+      shouldStartExternalBrowserPrompt({
+        hasInitialized: false,
+        isLoading: false,
+        loginStatus: "facebook",
+        isInAppBrowser: true,
+      }),
+    ).toBe(false);
+  });
+});