Hi everyone 👋🏼 I want to use a SharedFlow created with the

shareIn

operator +

WhileSubscribed

to cancel/resume the SharedFlow in

repeatOnLifecycle

when the Android App goes to background. It’s working fine so far. I also combine this flow with a MutableStateFlow in my ViewModel to react on user input and update my state.

class MyViewModel(
    dataSource: MyDataSource,
    sharingStarted: SharingStarted = WhileSubscribed(5000)
) : ViewModel() {

    var userInput = MutableStateFlow(1)

    val state = dataSource.dataFlow()
        .combine(userInput) { data, userInput ->
            OutputClass(data, userInput)
        }
        .shareIn(viewModelScope, sharingStarted, 1)

}

My issue is that I want to test this. I’ve tried to use Turbine for this but it does not help with the combine.

@Test
fun testMyViewModel() = runBlockingTest {

    val cut = MyViewModel(
        mockk { coEvery { dataFlow() } returns flowOf(Data()) },
        sharingStarted = SharingStarted.Eagerly
    )

    cut.state.test {

        // Also an emit to the userInput here does not help
        // cut.userInput.emit(2)
        
        assertEquals(OutputClass(...), awaitItem())
    }


}

I’m getting a timeout instead of the result.

I guess there’s some weird stuff when using Turbine with

runBlockingTest

state vs taskListState is a typo?

@ursus Sorry, yes it’s a typo

first try runBlocking instead of runBlockingTest, second try adding doOnNext on .state flow to see if it even emits at all + printlns inside my code.. thats how I deal with this

Thanks for helping out! Using

runBlocking

didn’t help. What solves the issue kind of is when I pass a scope to the ViewModel and use the TestCoroutineScope for the

shareIn

instead. But then I’ll get

Test finished with active jobs

Thats odd, all turbine does is suspend on awaitItem until the flow emits, so it shouldnt matter what scopes bla bla. If you remove the

shareIn

sharing, does it work?

Without the shareIn the tests are working fine (with Turbine). What I don’t understand is that the test is working when I don’t combine with the MutableStateFlow. I can test the

shareIn

without the combine

So it’s either testing

combine

or

shareIn

but not both?

Never used Turbine but docs suggest to me that you are missing

cancelAndConsumeRemainingEvents()

at end of

test

block.

test

doesn't return until

Flow

is complete or cancelled. The result of

shareIn

never completes so you need to cancel it. https://github.com/cashapp/turbine#hot-flows