I'm using Turbine library to test flows. It's work...

# coroutines

[Karan Sharma]

I'm using Turbine library to test flows. It's working really well for most use cases but this one got my head scratching.

private val _uiState: MutableStateFlow<UIState> = MutableStateFlow(UIState())
val uiState: StateFlow<UIState> = _uiState

private val _isActive: MutableStateFlow<Boolean> = MutableStateFlow(false)
val isActive: StateFlow<Boolean> = _isActive.onStart {
// SOME LOGIC THAT WILL UPDATE uiState flow meaning UIState object
}.stateIn(
scope = viewModelScope,
started = SharingStarted.WhileSubscribed(ABC_THRESHOLD.inWholeMilliseconds),
initialValue = true,
)


My question is how can I write a test for this scenario:
1. When isActive flow is started then UIState object has changes.

[Zach Klippenstein (he/him) [MOD]]

I don’t have an answer for your question, but this design looks problematic. Why are these two separate flows at all?

[jw]

You also don't need Turbine to test StateFlow. You can make a change, and then assert on .value directly.

[Karan Sharma]

@Zach Klippenstein (he/him) [MOD]
hmm, maybe there's a better way to do it, my use case is as follows:

1. UiState - Flow 1 -> Has the UiState object that displays data / loading / error etc.
2. isActive - Flow 2 -> Updates UiState periodically based on time, say every 10 seconds, change time value in the UIState.
3. Flow 3 -> Calls API every 30 seconds and this leads to updating of api data in UIState .
Therefore, kept them separate and this led to testing challenges. I will try the approach shared by @jw for this scenario, so I can still keep the logic in separate flows and be able to test it too.
But keen to hear if there are better ways to do this. 🙏

[Zach Klippenstein (he/him) [MOD]]

Why do you need a separate flow just to update UiState? Flows are for outputing values to consumers, if you have other work to do just put that in a normal coroutine.

[Karan Sharma]

The two other flows have an infinite while loop and they do something every x and y seconds respectively in the onStart.

I guess, will have to launch them in a separate coroutine inside onStart of uistate flow.

Will give this a shot.