dispatchers_unconfined_test.kt

@Test
fun `should change state to Playing after play() called`() = runTest(UnconfinedTestDispatcher()) {

    val soundPlayer = mockk<SoundPlayer>()
    coJustRun { soundPlayer.playSound() }

    val sut = MediaPlayer(this, soundPlayer)

    sut.playerState.test {
        awaitItem() shouldBe PlayerState.Stopped
        sut.play()
        awaitItem() shouldBe PlayerState.Playing
        cancelAndIgnoreRemainingEvents()
    }

}