Coroutine examples.kt

class Tests{ 
    @Test
    fun `Submits app selection if selections can be made`() = runBlocking(Dispatchers.Main) { //@Test... = runBlocking is a good convention
        mainActivityViewModel.submitAppSelection(selectedApp)
        
        verify(mockAppsStartupFsm).submitEvent(AppSelected(selectedApp))
        
    }
}

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

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

        // different strategy:
        // 1. explicitly move off Main thread because we **must have** parallelism (for some reason?)
        // 2. synchronize on the result, only after `submitEvent` returns (not suspends) will `submitAppSelection` return.
        withContext(Dispatchers.Default) { 
            appsStartupFsm.submitEvent(AppSelected(app))
        }
    }
}

Also worth noting, with a statement like lastSelectedApp = app, you might want to require that you're on the MainThread, surrounding the whole function with withContext(Dispatchers.Main), because if you dont you've got funny thread safety issues