test(app): add tests for RNFBAppModule setImmediate browser fallback

Author: just1and0

packages/app/__tests__/webAppModule.test.ts

@@ -0,0 +1,91 @@
+import { describe, expect, it, jest, beforeEach, afterEach } from '@jest/globals';
+
+jest.mock('react-native', () => ({
+  DeviceEventEmitter: {
+    emit: jest.fn(),
+  },
+}));
+
+jest.mock('../lib/internal/web/firebaseApp', () => ({
+  initializeApp: jest.fn(),
+  setLogLevel: jest.fn(),
+  getApp: jest.fn(),
+  getApps: jest.fn(() => []),
+  deleteApp: jest.fn(),
+}));
+
+const appModule = require('../lib/internal/web/RNFBAppModule.ts').default;
+
+describe('RNFBAppModule setImmediate guards', () => {
+  describe('with setImmediate available', () => {
+    beforeEach(() => {
+      jest.useFakeTimers();
+    });
+
+    afterEach(() => {
+      jest.useRealTimers();
+    });
+
+    it('eventsSendEvent uses setImmediate when available', () => {
+      const spy = jest.spyOn(globalThis, 'setImmediate');
+      appModule.eventsAddListener('test_event');
+      appModule.eventsNotifyReady(true);
+      appModule.eventsPing('test_event', { data: 1 });
+      expect(spy).toHaveBeenCalled();
+      spy.mockRestore();
+    });
+
+    it('eventsNotifyReady uses setImmediate when available', () => {
+      const spy = jest.spyOn(globalThis, 'setImmediate');
+      appModule.eventsNotifyReady(true);
+      expect(spy).toHaveBeenCalled();
+      spy.mockRestore();
+    });
+
+    it('eventsAddListener uses setImmediate when available', () => {
+      const spy = jest.spyOn(globalThis, 'setImmediate');
+      appModule.eventsAddListener('another_event');
+      expect(spy).toHaveBeenCalled();
+      spy.mockRestore();
+    });
+  });
+
+  describe('without setImmediate (browser environment)', () => {
+    let savedSetImmediate: typeof setImmediate;
+
+    beforeEach(() => {
+      jest.useFakeTimers();
+      savedSetImmediate = globalThis.setImmediate;
+      // @ts-expect-error — simulating browser where setImmediate is absent
+      delete globalThis.setImmediate;
+    });
+
+    afterEach(() => {
+      globalThis.setImmediate = savedSetImmediate;
+      jest.useRealTimers();
+    });
+
+    it('eventsSendEvent falls back to setTimeout', () => {
+      const spy = jest.spyOn(globalThis, 'setTimeout');
+      appModule.eventsAddListener('browser_event');
+      appModule.eventsNotifyReady(true);
+      appModule.eventsPing('browser_event', { data: 2 });
+      expect(spy).toHaveBeenCalled();
+      spy.mockRestore();
+    });
+
+    it('eventsNotifyReady falls back to setTimeout', () => {
+      const spy = jest.spyOn(globalThis, 'setTimeout');
+      appModule.eventsNotifyReady(true);
+      expect(spy).toHaveBeenCalled();
+      spy.mockRestore();
+    });
+
+    it('eventsAddListener falls back to setTimeout', () => {
+      const spy = jest.spyOn(globalThis, 'setTimeout');
+      appModule.eventsAddListener('browser_event_2');
+      expect(spy).toHaveBeenCalled();
+      spy.mockRestore();
+    });
+  });
+});