GreetingServiceRoboTest.kt

@RunWith(RobolectricTestRunner::class)
@Config(sdk = [Build.VERSION_CODES.P])
class GreetingServiceRoboTest {

    @get:Rule
    val mockitoRule: MockitoRule = MockitoJUnit.rule()

    @Mock
    lateinit var timeService: TimeService

    @Test
    fun testGreetingInTheMorning() {
        val testModule = module {
            bind<TimeService>().toInstance(object : TimeService {
                override fun getHourOfDay(): Int = 9
            })
        }
        KTP.openRootScope().installTestModules(testModule)
        val controller = Robolectric.buildActivity(MainActivity::class.java).setup()
        val textView = controller.get().findViewById<TextView>(R.id.greetingsTextView)
        Assert.assertEquals("Good morning, welcome to Toothpick", textView.text)
        Toothpick.reset()
    }

    @Test
    fun testGreetingInTheEvening() {
        val testModule = module {
            bind<TimeService>().toInstance(timeService)
        }
        whenever(timeService.getHourOfDay()).thenReturn(18)
        KTP.openRootScope().installTestModules(testModule)
        val controller = Robolectric.buildActivity(MainActivity::class.java).setup()
        val textView = controller.get().findViewById<TextView>(R.id.greetingsTextView)
        Assert.assertEquals("Good evening, welcome to Toothpick", textView.text)
        Toothpick.reset()
    }
}