Testing StateFlow not get all states

[mustafatatarhan0]

I tried to test StateFlows states. But I cannot get all states. Just last state what I getting. Here's my view model:

@HiltViewModel
class ExerciseViewModel @Inject constructor(
    private val exerciseRepository: BaseRepository,
    private val exerciseMapper: ExerciseMapper
) : ViewModel() {

    private val _data = MutableStateFlow(Exercise())
    val data: StateFlow<Exercise> = _data.asStateFlow()
    private val _state = MutableStateFlow<ExerciseViewState?>(null)
    val state: StateFlow<ExerciseViewState?> = _state.asStateFlow()

    fun loadExercise(id: Int) {
        viewModelScope.launch {
            try {
                _state.update { ExerciseViewState.Loading }
                val result = exerciseRepository.getExercise(id)
                _data.value = exerciseMapper.map(result)
                _state.value = ExerciseViewState.Data
            } catch (e: Exception) {
                _state.value = ExerciseViewState.Error
            }
        }
    }
}

And here's what I am trying to test:

@ExperimentalCoroutinesApi
class ExerciseViewModelTest {

    @get:Rule
    var rule = InstantTaskExecutorRule()

    @get:Rule
    val mainDispatcherRule = MainDispatcherRule()

    private var exerciseRepository = FakeExerciseRepository()
    private var exerciseMapper = ExerciseMapper()
    lateinit var viewModel: ExerciseViewModel

    @Before
    fun setUp() {
        MockKAnnotations.init(this)
        viewModel = ExerciseViewModel(
            exerciseRepository = exerciseRepository,
            exerciseMapper = exerciseMapper
        )
    }

    @Test
    fun loadExercise_ShouldSetLoadingState() = runTest {
        val stateList = mutableListOf<ExerciseViewState?>()
        val job = launch(UnconfinedTestDispatcher(testScheduler)) {
            viewModel.state.toList(stateList)
        }
        viewModel.loadExercise(id = 1)
        advanceUntilIdle()
        assertContains(stateList, ExerciseViewState.Loading)
        job.cancel()
    }
}

stateList returns only last state ([ExerciseViewState.Error]) I wanna reach all the values what states have. ([Loading,Data,Error])

[dkhalanskyjb]

Hi! This question was asked several times already: https://github.com/Kotlin/kotlinx.coroutines/issues?q=label%3Atest+StateFlow So, closing as duplicate. The discussion that is the simplest to follow is, in my opinion, this one: #3339

In general, for questions about usage, please use Stack Overflow or the Kotlin Slack channel.

[dkhalanskyjb]

The master issue for this topic is now #3939