What is the React Native testing strategy?

Testing in React Native uses similar tools to React web testing but with some mobile-specific considerations: Unit tests (Jest): test utility functions, business logic, reducers, hooks in isolation — no React Native rendering needed: // jest.config.js: preset: "react-native" // Mocks native modules automatically test("calculateTotal", () => { expect(calculateTotal([10, 20, 30])).toBe(60); });. Component tests (React Native Testing Library): import { render, fireEvent, screen } from "@testing-library/react-native"; test("button increments count", () => { render(<Counter />); fireEvent.press(screen.getByText("Increment")); expect(screen.getByText("Count: 1")).toBeTruthy(); }); // Mock hooks: jest.mock("@react-navigation/native", () => ({ useNavigation: () => ({ navigate: jest.fn() }), }));. Mocking native modules: // jest.setup.js: jest.mock("@react-native-async-storage/async-storage", () => require("@react-native-async-storage/async-storage/jest/async-storage-mock")); jest.mock("react-native-mmkv", () => ({ MMKV: jest.fn().mockImplementation(() => ({ set: jest.fn(), getString: jest.fn(), getBoolean: jest.fn(), })) }));. E2E tests (Detox): full end-to-end testing on iOS Simulator / Android Emulator. Actually interacts with the running app: describe("Login flow", () => { it("logs in with valid credentials", async () => { await element(by.id("email-input")).typeText("user@test.com"); await element(by.id("password-input")).typeText("password"); await element(by.id("login-button")).tap(); await expect(element(by.id("home-screen"))).toBeVisible(); }); });. Testing strategy: many unit tests (fast), fewer component tests, few E2E tests (slow). Mock all native modules in Jest. Use MSW (Mock Service Worker) or jest mocks for network requests. Snapshot tests for UI regression detection.