npm install -g appium

# Install per-platform drivers:
appium driver install xcuitest         # iOS
appium driver install uiautomator2     # Android
appium driver install espresso         # Android (alternative; gray-box)
appium driver install mac2             # macOS desktop
appium driver install windows          # Windows desktop

# Verify:
appium driver list

appium server -p 4723

import { remote } from 'webdriverio';

const capabilities = {
  platformName: 'Android',
  'appium:automationName': 'UiAutomator2',
  'appium:deviceName': 'Android Emulator',
  'appium:app': '/path/to/app.apk',
};

describe('Cart flow', () => {
  let driver;

  before(async () => {
    driver = await remote({
      hostname: 'localhost',
      port: 4723,
      capabilities,
    });
  });

  after(async () => {
    await driver.deleteSession();
  });

  it('adds an item to cart', async () => {
    const addButton = await driver.$('id=add_to_cart_button');
    await addButton.click();

    const cartCount = await driver.$('id=cart_count');
    const text = await cartCount.getText();
    expect(text).toBe('1');
  });
});

// By accessibility ID - the most cross-platform
await driver.$('~login-button').click();   // ~ prefix in WebdriverIO

// By id - works for both platforms with platform-prefixed IDs
await driver.$('id=add_to_cart_button');     // Android
await driver.$('id=add-to-cart-button');     // iOS uses accessibility ID

// XPath - works everywhere; brittle (selector-quality anti-pattern)
await driver.$('//XCUIElementTypeButton[@name="Submit"]');

// Image-based locator (Appium-specific) - fallback when no IDs
await driver.findElementByImage('./assets/login-button.png');

# Local with one platform
WDIO_OS=android wdio run wdio.conf.js

# Multi-platform: WebdriverIO multi-capability config
# wdio.conf.js
exports.config = {
    capabilities: [
        { platformName: 'iOS', 'appium:platformVersion': '17.4', ...iosCaps },
        { platformName: 'Android', 'appium:platformVersion': '14', ...androidCaps },
    ],
    runner: 'local',
    services: ['appium'],
};

# Multi-platform matrix
jobs:
  ui-tests:
    strategy:
      matrix:
        platform: [iOS, Android]
    runs-on: ${{ matrix.platform == 'iOS' && 'macos-15' || 'ubuntu-latest' }}
    steps:
      - uses: actions/checkout@v5

      - if: matrix.platform == 'Android'
        uses: reactivecircus/android-emulator-runner@v2
        with:
          api-level: 34
          script: WDIO_OS=android npx wdio run wdio.conf.js

      - if: matrix.platform == 'iOS'
        run: |
          xcrun simctl boot 'iPhone 15'
          WDIO_OS=ios npx wdio run wdio.conf.js