Use separate Selenium and Appium sessions together to test web and mobile app interaction.

testCustomerDeviceAndBaristaTerminalTogether.java

public void testCustomerDeviceAndBaristaTerminalTogether()
{
	// Create two sessions in one test -- one on a browser for the barista and one on a mobile device for the customer
	browser = new RemoteWebDriver(seleniumServerURL, browserCapabilites);
	phone = new AppiumDriver(appiumServerURL, deviceCapabilities);

	// Barista logs into terminal app in browser
	browser.get(baristaApp.loginPage.url);
	browser.findElement(baristaApp.loginPage.usernameField).sendKeys(barista.username);
	browser.findElement(baristaApp.loginPage.passwordField).sendKeys(barista.password);
	browser.findElement(baristaApp.loginPage.loginButton).click();
	
	// Customer logs into mobile app on mobile device
	phone.findElement(mobileApp.loginScreen.usernameField).sendKeys(customer.username);
	phone.findElement(mobileApp.loginScreen.passwordField).sendKeys(customer.password);
	phone.findElement(mobileApp.loginScreen.loginButton).click();

	// Customer selects a coffee -- after login succeeded
	coffeeButton = phoneWait.until(ExpectedConditions.elementToBeClickable(mobileApp.menuScreen.coffeeButton));
	coffeeButton.click();

	// Barista receives the order and marks it out of stock 
	browserWait.until(ExpectedConditions.visibilityOfElementLocated(baristaApp.orderDialog));
	browser.findElement(baristaApp.orderDialog.outOfStockButton).click();

	// Customer is prompted to cancel or place new order
	orderConfirmationDialog = phoneWait.until(ExpectedConditions.visibilityOfElementLocated(mobileApp.orderConfirmationDialog));

	// User receives out of stock notification and can cancel or place new order
	assertThat(orderConfirmationDialog.getText()).contains("Out of Stock");
	assertThat(orderConfirmationDialog.findElement(By.accessibilityId("Cancel Order"))).exists();
	assertThat(orderConfirmationDialog.findElement(By.accessibilityId("Place New Order"))).exists();
}