Sign In error verification Android UI tests with Appium

AppiumSignInTest.kt

class AppiumSignInTest {

    private lateinit var appiumDriver: AppiumDriver<AndroidElement>

    @Before
    fun setup() {
        val capabilities = DesiredCapabilities()
        capabilities.setCapability(MobileCapabilityType.PLATFORM_NAME, "Android")
        capabilities.setCapability(MobileCapabilityType.DEVICE_NAME, "emulator-5554")
        capabilities.setCapability("appPackage", "com.alex.mapnotes")
        capabilities.setCapability("appActivity", "com.alex.mapnotes.splash.SplashActivity")

        appiumDriver = AndroidDriver(URL("http://0.0.0.0:4723/wd/hub"), capabilities)
    }

    @Test
    fun shouldDisplaySinInErrorWhenEmailIsIncorrect() {
        val emailValue = "test"
        val expectedErrorMessage = "An email address should be valid"

        openSignInScreen()

        val emailInputField = appiumDriver.findElement(By.id("email"))
        emailInputField.setValue(emailValue)

        appiumDriver.hideKeyboard()

        val signInButton = appiumDriver.findElement(By.id("signIn"))
        signInButton.click()

        val snacknarError = appiumDriver.findElement(By.xpath("//*[@text='$expectedErrorMessage']"))
        assertNotNull(snacknarError)
    }

    @After
    fun tearDown() {
        appiumDriver.quit()
    }

    private fun openSignInScreen() {
        val signIn = appiumDriver.findElement(By.id("signIn"))
        signIn.click()
    }
}