I need to unit-test the code involving a `scan` operator and hot event stream. Basically I want to c...

# coroutines

[dimsuz]

I need to unit-test the code involving a scan operator and hot event stream. Basically I want to configure the flow, send events and verify they are received:

runBlocking(Dispatchers.Default) {
    val events = BroadcastChannel<Int>(capacity = Channel.BUFFERED)
    launch {
      events.asFlow().scan(1) { accumulator, value -> value }
        .take(2)
        .collect { println("received $it") }
    }
    launch {
      events.send(42)
    }
  }

The above doesn't work, it receives 1(inital accum) item and then hangs indefinitely, because send is done before collect begins.
I tried moving send inside the collect, after initial element is received, but this doesn't work, because scan is implemented so that its internal collect also starts after my send is called (it starts after first collection completes).

Any advice on how to do that?

[ildar.i [Android]]

As I can see, you're sending only one element (42)

[dimsuz]

Yep, the first one is an initial accumulator of scan: scan(1) {...} , it will be emitted right away.