Mobile App Testing

---
name: mobile-app-testing
description: Mobile app testing with unit tests, UI automation, performance testing. Use for test infrastructure, E2E tests, testing standards, or encountering test framework setup, device farms, flaky tests, platform-specific test errors.
keywords: mobile testing, unit testing, UI automation, E2E testing, Jest, XCTest, JUnit, Detox, Espresso, Appium, React Native testing, iOS testing, Android testing, test framework, device farms, flaky tests, mobile test automation, integration testing, testing pyramid, test coverage
---

# Mobile App Testing

Implement comprehensive testing strategies for mobile applications.

## Testing Pyramid

| Level | Tools | Coverage |
|-------|-------|----------|
| Unit | Jest, XCTest, JUnit | 70% |
| Integration | Detox, Espresso | 20% |
| E2E | Appium, Detox | 10% |

## React Native (Jest + Detox)

```javascript
// Unit test
describe('CartService', () => {
  it('calculates total correctly', () => {
    const cart = new CartService();
    cart.addItem({ price: 10, quantity: 2 });
    expect(cart.getTotal()).toBe(20);
  });
});

// E2E test (Detox)
describe('Login flow', () => {
  beforeEach(async () => {
    await device.reloadReactNative();
  });

  it('should login successfully', async () => {
    await element(by.id('email-input')).typeText('user@example.com');
    await element(by.id('password-input')).typeText('password123');
    await element(by.id('login-button')).tap();
    await expect(element(by.id('dashboard'))).toBeVisible();
  });
});
```

## iOS (XCTest)

```swift
func testLoginSuccess() {
    let app = XCUIApplication()
    app.launch()

    app.textFields["email"].tap()
    app.textFields["email"].typeText("user@example.com")
    app.secureTextFields["password"].typeText("password123")
    app.buttons["Login"].tap()

    XCTAssertTrue(app.staticTexts["Welcome"].exists)
}
```

## Android (Espresso)

```kotlin
@Test
fun loginSuccess() {
    onView(withId(R.id.email)).perform(typeText("user@example.com"))
    onView(withId(R.id.password)).perform(typeText("password123"))
    onView(withId(R.id.loginButton)).perform(click())
    onView(withId(R.id.dashboard)).check(matches(isDisplayed()))
}
```

## Best Practices

- Test business logic first (unit tests)
- Mock external dependencies
- Test both success and failure paths
- Automate critical user flows
- Maintain >80% code coverage
- Test on real devices periodically

## Avoid

- Testing implementation details
- Hardcoded test data
- Interdependent tests
- Skipping error case testing