i’m having trouble with verification of suspending functions with mockito failing randomly. the test...

# test

[matt tighe]

i’m having trouble with verification of suspending functions with mockito failing randomly. the tests most often pass, but will occasionally fail and i’m not sure why. for example:

@Test
    fun `Submits app selection if selections can be made`() {
        mainActivityViewModel.submitAppSelection(selectedApp)

        runBlocking {
            verify(mockAppsStartupFsm).submitEvent(AppSelected(selectedApp))
        }
    }

class MainActivityViewModel {
    fun submitAppSelection(app: App) {
        if (!selectionsCanBeMade()) return
        lastSelectedApp = app

        val coroutineScope = CoroutineScope(Dispatchers.Default)
        coroutineScope.launch { appsStartupFsm.submitEvent(AppSelected(app)) }
    }
}

AppsStartupFsm#submitEvent is a suspending function.
Changing the runBlocking scope to be function level doesn’t seem to help. Is there something I’m missing with verification of suspending functions?

[Saiedmomen]

Its supposed to work
https://github.com/Kotlin/kotlinx.coroutines/blob/master/core/kotlinx-coroutines-test/README.md

[Saiedmomen]

It didn't work for me though

[Saiedmomen]

If you got it to work I'd be really happy to hear about it 🙂

[matt tighe]

The issue is that launch may not actually launch the coroutine before verify runs. Verification of suspending functions works, you just have to do it right. I’m still working on how to fix it in my own code. In the simplified example I posted it would need to be something like

suspend fun submitAppSelection(app: App) {
        if (!selectionsCanBeMade()) return
        lastSelectedApp = app

        appsStartupFsm.submitEvent(AppSelected(app)
    }

[matt tighe]

and then use runblocking scope for entire test function

[Saiedmomen]

I don't think moving scope to activity/fragment is a good idea

[Saiedmomen]

Are you using coroutines android and Dispatchers.Main?