Hi! Please help me understand why this hangs after printing 1,2,3 and how do I unfreeze it?...

runBlocking {
    val events = BroadcastChannel<Int>(capacity = Channel.BUFFERED)
    merge(events.asFlow(), flowOf(1,2,3))
      .onStart { events.offer(42) }
      .take(4)
      .collect {
        println("received $it")
      }
  }

This popped up while I was trying to write a unit test for a certain api and got me puzzled. It looks like event should be buffered in a non-blocking way. I also use

.take(4)

to unsubscribe from hot Flow, but it's that

42

never gets seen somehow.

Because onStart is called before subscribing to flow. So you offered an element to channel before subscribing to it. Buffered broadcast channel doesn`t replay last element, so 42 is just lost

thanks!