Testing Capacitor Applications

Comprehensive testing strategies for Capacitor mobile apps.

When to Use This Skill

• User wants to add tests
• User asks about testing strategies
• User needs E2E testing
• User wants to mock native plugins
• User needs CI testing setup

Testing Pyramid

        /\
       /  \        E2E Tests (Few)
      /----\       - Real devices
     /      \      - Full user flows
    /--------\     Integration Tests (Some)
   /          \    - Component interactions
  /------------\   - API integration
 /              \  Unit Tests (Many)
/----------------\ - Pure functions
                   - Business logic

Unit Testing

Setup with Vitest

bun add -D vitest @vitest/coverage-v8

// vitest.config.ts
import { defineConfig } from 'vitest/config';

export default defineConfig({
  test: {
    globals: true,
    environment: 'jsdom',
    coverage: {
      provider: 'v8',
      reporter: ['text', 'json', 'html'],
    },
    setupFiles: ['./src/test/setup.ts'],
  },
});

Mock Capacitor Plugins

// src/test/setup.ts
import { vi } from 'vitest';

// Mock @capacitor/core
vi.mock('@capacitor/core', () => ({
  Capacitor: {
    isNativePlatform: vi.fn(() => true),
    getPlatform: vi.fn(() => 'ios'),
    isPluginAvailable: vi.fn(() => true),
  },
  registerPlugin: vi.fn(),
}));

// Mock @capacitor/preferences
vi.mock('@capacitor/preferences', () => ({
  Preferences: {
    get: vi.fn(),
    set: vi.fn(),
    remove: vi.fn(),
    clear: vi.fn(),
  },
}));

// Mock @capgo/capacitor-native-biometric
vi.mock('@capgo/capacitor-native-biometric', () => ({
  NativeBiometric: {
    isAvailable: vi.fn().mockResolvedValue({
      isAvailable: true,
      biometryType: 'touchId',
    }),
    verifyIdentity: vi.fn().mockResolvedValue({}),
    setCredentials: vi.fn().mockResolvedValue({}),
    getCredentials: vi.fn().mockResolvedValue({
      username: 'test@example.com',
      password: 'token',
    }),
  },
}));

Unit Test Examples

// src/services/auth.test.ts
import { describe, it, expect, vi, beforeEach } from 'vitest';
import { AuthService } from './auth';
import { NativeBiometric } from '@capgo/capacitor-native-biometric';

describe('AuthService', () => {
  beforeEach(() => {
    vi.clearAllMocks();
  });

  describe('biometricLogin', () => {
    it('should authenticate with biometrics', async () => {
      const authService = new AuthService();

      const result = await authService.biometricLogin();

      expect(NativeBiometric.verifyIdentity).toHaveBeenCalledWith({
        reason: 'Authenticate to login',
        title: 'Biometric Login',
      });
      expect(result).toBe(true);
    });

    it('should return false when biometrics unavailable', async () => {
      vi.mocked(NativeBiometric.isAvailable).mockResolvedValueOnce({
        isAvailable: false,
        biometryType: 'none',
      });

      const authService = new AuthService();
      const result = await authService.biometricLogin();

      expect(result).toBe(false);
    });

    it('should handle user cancellation', async () => {
      vi.mocked(NativeBiometric.verifyIdentity).mockRejectedValueOnce(
        new Error('User cancelled')
      );

      const authService = new AuthService();
      const result = await authService.biometricLogin();

      expect(result).toBe(false);
    });
  });
});

Testing Utilities

// src/test/utils.ts
import { Capacitor } from '@capacitor/core';
import { vi } from 'vitest';

export function mockPlatform(platform: 'ios' | 'android' | 'web') {
  vi.mocked(Capacitor.getPlatform).mockReturnValue(platform);
  vi.mocked(Capacitor.isNativePlatform).mockReturnValue(platform !== 'web');
}

export function mockPluginAvailable(available: boolean) {
  vi.mocked(Capacitor.isPluginAvailable).mockReturnValue(available);
}

// Usage in tests
describe('Platform-specific behavior', () => {
  it('should use iOS-specific code on iOS', () => {
    mockPlatform('ios');
    // Test iOS behavior
  });

  it('should use Android-specific code on Android', () => {
    mockPlatform('android');
    // Test Android behavior
  });
});

Component Testing

React Testing Library

bun add -D @testing-library/react @testing-library/user-event

// src/components/LoginButton.test.tsx
import { render, screen, waitFor } from '@testing-library/react';
import userEvent from '@testing-library/user-event';
import { LoginButton } from './LoginButton';
import { NativeBiometric } from '@capgo/capacitor-native-biometric';

describe('LoginButton', () => {
  it('should show biometric option when available', async () => {
    render(<LoginButton />);

    await waitFor(() => {
      expect(screen.getByText('Login with Face ID')).toBeInTheDocument();
    });
  });

  it('should call biometric auth on click', async () => {
    const user = userEvent.setup();
    render(<LoginButton />);

    const button = await screen.findByRole('button', { name: /face id/i });
    await user.click(button);

    expect(NativeBiometric.verifyIdentity).toHaveBeenCalled();
  });
});

Vue Test Utils

bun add -D @vue/test-utils

// src/components/LoginButton.spec.ts
import { mount, flushPromises } from '@vue/test-utils';
import LoginButton from './LoginButton.vue';
import { NativeBiometric } from '@capgo/capacitor-native-biometric';

describe('LoginButton', () => {
  it('should render biometric button', async () => {
    const wrapper = mount(LoginButton);
    await flushPromises();

    expect(wrapper.text()).toContain('Login with Biometrics');
  });

  it('should trigger authentication on click', async () => {
    const wrapper = mount(LoginButton);
    await flushPromises();

    await wrapper.find('button').trigger('click');

    expect(NativeBiometric.verifyIdentity).toHaveBeenCalled();
  });
});

E2E Testing

Playwright for Web

bun add -D @playwright/test
bunx playwright install

// playwright.config.ts
import { defineConfig, devices } from '@playwright/test';

export default defineConfig({
  testDir: './e2e',
  fullyParallel: true,
  use: {
    baseURL: 'http://localhost:5173',
    trace: 'on-first-retry',
  },
  projects: [
    {
      name: 'chromium',
      use: { ...devices['Desktop Chrome'] },
    },
    {
      name: 'Mobile Safari',
      use: { ...devices['iPhone 14'] },
    },
    {
      name: 'Mobile Chrome',
      use: { ...devices['Pixel 7'] },
    },
  ],
  webServer: {
    command: 'bun run dev',
    url: 'http://localhost:5173',
    reuseExistingServer: !process.env.CI,
  },
});

// e2e/login.spec.ts
import { test, expect } from '@playwright/test';

test.describe('Login Flow', () => {
  test('should login with email and password', async ({ page }) => {
    await page.goto('/login');

    await page.fill('[data-testid="email"]', 'test@example.com');
    await page.fill('[data-testid="password"]', 'password123');
    await page.click('[data-testid="login-button"]');

    await expect(page).toHaveURL('/dashboard');
    await expect(page.locator('h1')).toContainText('Welcome');
  });

  test('should show error for invalid credentials', async ({ page }) => {
    await page.goto('/login');

    await page.fill('[data-testid="email"]', 'wrong@example.com');
    await page.fill('[data-testid="password"]', 'wrong');
    await page.click('[data-testid="login-button"]');

    await expect(page.locator('[data-testid="error"]')).toBeVisible();
  });
});

Appium for Native

bun add -D webdriverio @wdio/appium-service @wdio/mocha-framework

// wdio.conf.ts
export const config: WebdriverIO.Config = {
  runner: 'local',
  specs: ['./e2e/native/**/*.spec.ts'],
  capabilities: [
    {
      platformName: 'iOS',
      'appium:deviceName': 'iPhone 15',
      'appium:platformVersion': '17.0',
      'appium:app': './ios/App/build/App.app',
      'appium:automationName': 'XCUITest',
    },
    {
      platformName: 'Android',
      'appium:deviceName': 'Pixel 8',
      'appium:platformVersion': '14',
      'appium:app': './android/app/build/outputs/apk/debug/app-debug.apk',
      'appium:automationName': 'UiAutomator2',
    },
  ],
  services: ['appium'],
  framework: 'mocha',
};

// e2e/native/login.spec.ts
describe('Native Login', () => {
  it('should login with biometrics', async () => {
    // Wait for app to load
    await $('~login-screen').waitForExist();

    // Tap biometric button
    await $('~biometric-login').click();

    // Simulate biometric auth (device-specific)
    if (driver.isIOS) {
      await driver.touchId(true);
    } else {
      await driver.fingerPrint(1);
    }

    // Verify logged in
    await expect($('~dashboard')).toBeExisting();
  });
});

Detox for React Native Style Testing

bun add -D detox

// .detoxrc.js
module.exports = {
  testRunner: {
    $0: 'jest',
    args: {
      config: 'e2e/jest.config.js',
    },
  },
  apps: {
    'ios.debug': {
      type: 'ios.app',
      binaryPath: 'ios/App/build/App.app',
      build: 'cd ios && xcodebuild ...',
    },
    'android.debug': {
      type: 'android.apk',
      binaryPath: 'android/app/build/outputs/apk/debug/app-debug.apk',
      build: 'cd android && ./gradlew assembleDebug',
    },
  },
  devices: {
    simulator: {
      type: 'ios.simulator',
      device: { type: 'iPhone 15' },
    },
    emulator: {
      type: 'android.emulator',
      device: { avdName: 'Pixel_8_API_34' },
    },
  },
};

Native Testing

iOS XCTest

// ios/AppTests/PluginTests.swift
import XCTest
@testable import App
import Capacitor

class PluginTests: XCTestCase {
    var bridge: MockBridge!

    override func setUp() {
        super.setUp()
        bridge = MockBridge()
    }

    func testPluginMethodReturnsExpectedValue() {
        let plugin = MyPlugin(bridge: bridge, pluginId: "MyPlugin", pluginName: "MyPlugin")

        let call = CAPPluginCall(callbackId: "test", options: ["value": "test"], success: { result, call in
            XCTAssertEqual(result?.data?["value"] as? String, "test")
        }, error: { error in
            XCTFail("Should not error")
        })

        plugin.echo(call!)
    }
}

Android JUnit

// android/app/src/test/java/com/example/PluginTest.kt
import org.junit.Test
import org.junit.Assert.*
import org.mockito.Mockito.*

class PluginTest {
    @Test
    fun `echo returns input value`() {
        val plugin = MyPlugin()
        val call = mock(PluginCall::class.java)

        `when`(call.getString("value")).thenReturn("test")

        plugin.echo(call)

        verify(call).resolve(argThat { data ->
            data.getString("value") == "test"
        })
    }
}

Android Instrumented Tests

// android/app/src/androidTest/java/com/example/PluginInstrumentedTest.kt
import androidx.test.ext.junit.runners.AndroidJUnit4
import androidx.test.platform.app.InstrumentationRegistry
import org.junit.Test
import org.junit.runner.RunWith
import org.junit.Assert.*

@RunWith(AndroidJUnit4::class)
class PluginInstrumentedTest {
    @Test
    fun useAppContext() {
        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
        assertEquals("com.example.app", appContext.packageName)
    }
}

Testing Best Practices

Test Organization

src/
├── components/
│   ├── Button.tsx
│   └── Button.test.tsx      # Unit tests next to component
├── services/
│   ├── auth.ts
│   └── auth.test.ts
├── test/
│   ├── setup.ts             # Test setup
│   ├── mocks/               # Shared mocks
│   └── utils.ts             # Test utilities
e2e/
├── web/                     # Playwright tests
│   └── login.spec.ts
└── native/                  # Appium tests
    └── login.spec.ts

Mock Best Practices

// Don't over-mock - test real behavior when possible
// BAD
vi.mock('./api', () => ({
  fetchUser: vi.fn().mockResolvedValue({ id: 1, name: 'Test' }),
}));

// GOOD - Use MSW for API mocking
import { setupServer } from 'msw/node';
import { rest } from 'msw';

const server = setupServer(
  rest.get('/api/user', (req, res, ctx) => {
    return res(ctx.json({ id: 1, name: 'Test' }));
  })
);

beforeAll(() => server.listen());
afterEach(() => server.resetHandlers());
afterAll(() => server.close());

CI Configuration

# .github/workflows/test.yml
name: Tests

on: [push, pull_request]

jobs:
  unit:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: oven-sh/setup-bun@v1
      - run: bun install
      - run: bun test --coverage

  e2e:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: oven-sh/setup-bun@v1
      - run: bun install
      - run: bunx playwright install --with-deps
      - run: bun run build
      - run: bunx playwright test

  ios:
    runs-on: macos-latest
    steps:
      - uses: actions/checkout@v4
      - run: cd ios/App && xcodebuild test -scheme App -destination 'platform=iOS Simulator,name=iPhone 15'

  android:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-java@v4
        with:
          java-version: '17'
          distribution: 'temurin'
      - run: cd android && ./gradlew test

Resources

• Vitest Documentation: https://vitest.dev
• Playwright Documentation: https://playwright.dev
• Testing Library: https://testing-library.com
• Appium Documentation: https://appium.io