Anyone know if there’s any easy way to get a robolectric test to wait for a coroutine launched by a ...

# compose

[mattinger]

Anyone know if there’s any easy way to get a robolectric test to wait for a coroutine launched by a “rememberCoroutineScope” scope?

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

I think you’d need to register your own idling resource. Animations do this automatically, but if you’re launching your own coroutines you probably need to do it yourself.

[mattinger]

For expresso tests, yes @Zach Klippenstein (he/him) [MOD]. This is in a robolectric test, which does’t necessarily use idling resources. I have that already, and have a rule i can use in an espresso test. But this is robolectric not espresso

[mattinger]

I suppose i could sort of manually simulate it:

runBlocking {
            while (!EspressoIdlingResource.getIdlingResource().isIdleNow()) {
                delay(100L)
            }
        }

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

oh sorry, misread.

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

yea i’m not sure for robolectric

[mattinger]

I’m also having problems with the viewpager and figuring out what’s visible

[Jason Ankers]

If you’re not swapping dispatchers it should just work fine, rememberCoroutineScope should be using TestCoroutineDispatcher in tests

[mattinger]

It’s just odd @Jason Ankers because i’m using an animateScrollTo with a horizontal pager. That’s triggering a page change, which i’m listening to here:

LaunchedEffect(pagerState) {
        snapshotFlow { pagerState.currentPage }.collect { page ->
            println("onPageChange ${items[page].page}")
            onPageChange(items[page].page)
        }
    }

[mattinger]

but onPageChange isn’t firing immediate like i would think it would with a TestCoroutineDispatcher. If i put my condition checking for that execution later on in the code, it’s fine.

[mattinger]

I’m also struggling to figure out how to test that the right pager contents are on screen,s icne the semantic tree for the pager doesn’t seem to tell me that.