Different behaviour when using coroutines 1.6.0
See original GitHub issueAs an example I would like to suggest following test:
private val stateFlow = MutableStateFlow(0)
private val flow: Flow<Int> = stateFlow
@Test
fun `turbine test`() = runBlockingTest {
Dispatchers.setMain(TestCoroutineDispatcher())
val scope = CoroutineScope(Job() + Dispatchers.Main)
flow.test {
flowOf(1, 2, 3)
.onEach { stateFlow.value = it }
.launchIn(scope)
val events = cancelAndConsumeRemainingEvents()
}
Dispatchers.resetMain()
}
When using coroutines 1.5.2, as expected events
variable will be a list with size of 4 which contains integers wrapped in Item
class: [Item(0), Item(1), Item(2), Item(3)]
But when using coroutines 1.6.0 like so:
private val stateFlow = MutableStateFlow(0)
private val flow: Flow<Int> = stateFlow
@Test
fun `turbine test`() = runTest {
Dispatchers.setMain(UnconfinedTestDispatcher())
val scope = CoroutineScope(Job() + Dispatchers.Main)
flow.test {
flowOf(1, 2, 3)
.onEach { stateFlow.value = it }
.launchIn(scope)
val events = cancelAndConsumeRemainingEvents()
}
Dispatchers.resetMain()
}
events
will contain only the first and last items: [Item(0), Item(3)].
Also if I use StandardTestDispatcher
instead of UnconfinedTestDispatcher
, events
will contain only the first item: [Item(0)].
Is it expected behaviour? Do I need to adjust my test somehow to get the same results as for coroutines version 1.5.2?
Issue Analytics
- State:
- Created 2 years ago
- Reactions:3
- Comments:8 (2 by maintainers)
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Top GitHub Comments
The timeout is gone on
trunk
as it is now provided byrunTest
automatically.Thank you for your reply @mhernand40 but I see only the first and the last values in case I use
UnconfinedTestDispatcher
, not theStandardTestDispatcher
. Also it does not matter if I useDispatchers.setMain
inside the test or using@Before
function - the result is the same, I receive only the first and the last emission. You can see that I don’t use scope provided byrunTest
, I create a scope manually usingJob() + Dispatchers.Main
and at the time of creating this scopeDispatchers.Main
is already substituted withUnconfinedTestDispatcher
.