I want to control whether `delay(..)` reports IDLE...

# coroutines

[zak.taccardi]

I want to control whether delay(..) reports IDLE or not in an Espresso test dynamically at runtime. What would be the right way to handle this?.

For example, if a delay(..) launched on Dispatchers.Default is currently suspended, I would like to be able to control at any point through the test whether the dispatcher should report idle or not

[Zach Klippenstein (he/him) [MOD]]

You could wrap the dispatchers you're injecting for your tests in ones that tracks delays as idling resources or something. I haven't tried this but it seems like it should work?

For that matter, to be more general, you could also probably just wrap your dispatchers with a ContinuationInterceptor that reports all unresumed continuations as idling resources. But I'm not sure if that would handle cancellation.

[zak.taccardi]

the app needs to report idle only when all coroutines are suspended

[zak.taccardi]

but this doesn’t account for delay(..) or ongoing coroutines (actor coroutine)

[zak.taccardi]

I was able to get this working I think by creating a new CoroutineDispatcher that wrapped Dispatchers.Default and implemented an internal API for Delay

[zak.taccardi]

https://github.com/Kotlin/kotlinx.coroutines/issues/1919

[zak.taccardi]

The coroutines team needs to do a better job of providing APIs and clear guidance for Espresso idling in my opinion

[zak.taccardi]

obviously a non-trivial task too

[rkeazor]

@zak.taccardi I think the most common practice, if not the best practice is to use Idiling Resources. Than you can just focus on working with the counter, rather than the coroutine

[rkeazor]

This seems like a good article https://medium.com/@michaelbukachi/coroutines-and-idling-resources-c1866bfa5b5d