Regression: Testing MutableSharedFlow(extraBufferCapacity = 1) + flatMapLatest + tryEmit results in awaitItem() timeout

The following test passes on 0.8.0 but fails on 0.9.0 due to a timeout with awaitItem():

  @Test
  fun repro() = runTest(dispatchTimeoutMs = 100L) {
    val sharedFlow = MutableSharedFlow<Int>(extraBufferCapacity = 1)
    sharedFlow
        .flatMapLatest { value -> flowOf(value) }
        .test {
          sharedFlow.tryEmit(1)
          assertThat(awaitItem()).isEqualTo(1)
        }
  }

Observations:

• Test passes when using flatMapConcat instead of flatMapLatest
• Test passes if replay = 1 is used instead of extraBufferCapacity = 1.
• Test passes if runTest(UnconfinedTestDispatcher()) is used.
• Test still fails if sharedFlow.emit(1) is used instead of sharedFlow.tryEmit(1).

I’m using Kotlin 1.7.10 and Coroutines 1.6.4.

[JakeWharton]

Nevermind I forgot to pull trunk before testing. Your test passes on the latest. So this is a dupe of #138.

[mhernand40]

The snippet I pasted in the Issue Summary is a dumbed down version of a scenario one of my team project’s tests was running. I have confirmed that with 0.10.0 the test now passes. 👍