Sign In error verification Android UI tests with UiAutomator

UiAutomatorSignInTest.kt

@RunWith(AndroidJUnit4::class)
class UiAutomatorSignInTest {

    companion object {
        const val LAUNCH_TIMEOUT = 2_000L
        const val APP_PACKAGE = "com.alex.mapnotes"
    }

    private val device = UiDevice.getInstance(InstrumentationRegistry.getInstrumentation())

    private fun openApp(packageName: String) {
        device.pressHome()

        // Wait for launcher
        val launcherPackage: String = device.launcherPackageName
        assertThat(launcherPackage, notNullValue())
        device.wait(
                Until.hasObject(By.pkg(launcherPackage).depth(0)),
                LAUNCH_TIMEOUT
        )

        // Start an activity
        val context = ApplicationProvider.getApplicationContext<Context>()
        val intent = context.packageManager.getLaunchIntentForPackage(packageName)
                .apply { addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK) }
        context.startActivity(intent)

        // Wait for the app to appear
        device.wait(Until.hasObject(By.pkg(APP_PACKAGE).depth(0)),
                LAUNCH_TIMEOUT)
    }

    private fun navigateToSignIn() {
        device.wait(Until.hasObject(By.res("com.alex.mapnotes:id/signIn")), LAUNCH_TIMEOUT)
        val login: UiObject2 = device.findObject(By.res("com.alex.mapnotes:id/signIn"))
        if (login.isEnabled) {
            login.click()
        }
        device.wait(Until.hasObject(By.res("com.alex.mapnotes:id/signIn")), LAUNCH_TIMEOUT)
    }

    @Test
    fun shouldDisplaySinInErrorWhenEmailIsIncorrect() {
        openApp(APP_PACKAGE)
        navigateToSignIn()

        val incorrectEmail = "test"
        val expectedErrorMessage = "An email address should be valid"

        val emailInput: UiObject2 = device.findObject(By.res("com.alex.mapnotes:id/email"))
        emailInput.text = incorrectEmail

        val signInButton: UiObject2 = device.findObject(By.res("com.alex.mapnotes:id/signIn"))
        if (signInButton.isEnabled) {
            signInButton.click()
        }

        device.wait(Until.hasObject(By.text(expectedErrorMessage)), LAUNCH_TIMEOUT)
        val errorMessage = device.findObject(By.text(expectedErrorMessage))
        assertEquals(expectedErrorMessage, errorMessage.text)
    }
}