MVVMTesting8.kt

class MainViewModelTest {

    @get:Rule
    val mainCoroutineRule = MainCoroutineRule()

    private val userServices = mock<UserServices>()

    private lateinit var viewModel: MainViewModel

    private val testDispatcher = AppDispatchers(
        IO = TestCoroutineDispatcher(),
        MAIN = Dispatchers.Unconfined
    )

    @Test
    fun `Loading state works`() = runBlocking {
        whenever(userServices.getUsers()).doSuspendableAnswer {
            withContext(Dispatchers.IO) { delay(5000) }
            emptyList()
        }

        viewModel = MainViewModel(userServices, testDispatcher)
        Assert.assertEquals(State.LOADING, viewModel.state.value)
    }
}