How can I test back-pressure?

Hi, I was wondering if there is any mechanism to test the same back-pressure behavior that collect() has. Here is an example on the different behaviors I encounter.

@Test
public fun `when I test - flow should backpressure`(): TestResult = runTest {
    val myFlow:Flow<Int> = flow {
        println("emitting 1")
        emit(1)
        println("emitted 1")
        delay(10)
        println("emitting 2")
        emit(2)
        println("emitted 2")
        delay(10)
        println("emitting 3")
        emit(3)
        println("emitted 3")
    }


    println("COLLECT")
    myFlow.collect {
        println("collected $it")
        delay(50)
    }

    println()
    println("TEST")
    // Test
    myFlow.test {
        val item1 = awaitItem()
        println("collected $item1")
        delay(50)
        val item2 = awaitItem()
        println("collected $item2")
        delay(50)
        val item3 = awaitItem()
        println("collected $item3")
        awaitComplete()
    }
}

Prints

COLLECT
emitting 1
collected 1
emitted 1
emitting 2
collected 2
emitted 2
emitting 3
collected 3
emitted 3

TEST
emitting 1
emitted 1
emitting 2
emitted 2
emitting 3
emitted 3
collected 1
collected 2
collected 3

[JakeWharton]

We can possibly design a variation of the API that allows applying backpressure by using a channel with a smaller buffer and potentially an intermediate coroutine which controls the number of allowed items before it blocks the collector.

[JakeWharton]

I mean we can omit it and start with only two modes: rendezvous or unlimited buffer. If someone complains at least we have an idea on how to build support for arbitrary buffer capacities, but maybe no one actually needs it.