i’m having trouble unit testing a flow. i have a `ViewModel` that converts a flow from my DB into a ...

# android

[matt tighe]

i’m having trouble unit testing a flow. i have a ViewModel that converts a flow from my DB into a livedata for the view layer. the VM extends coroutine scope.

viewState.postValue(ViewState(loading = true))
this.launch {
    repository.observeAll().collect { observedList ->
        viewState.postValue(ViewState(list = observedList))
    }
}

and then in my test I’d like to do something like this:

val expectedList = listOf(Thing())
coEvery { mockRepo.observeAll() } returns flow {
    emit(expectedList)
}

viewModel.submitAction(Action.Refresh)

coVerify {
    mockRepo.observeAll()
    mockViewStateObserver.onChanged(ViewState(loading = true, list = listOf()))
    mockViewStateObserver.onChanged(ViewState(loading = false, list = expectedList))
}

but the coVerify coroutine completes before the second update to the LiveData. anyone have suggestions besides injecting the test scope or delaying?

[reline]

have you tried runBlockingTest from kotlinx-coroutines-test? It should ensure to run everything in coVerify before continuing.

[matt tighe]

that totally does the trick. thanks