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I still haven't managed to verify that a suspending function is called in tests. I created a minimal project demonstrating the problem on GitHub - <https://github.com/curioustechizen/kotlin-coroutines-test-issue>

If anyone has any ideas please let me know.

You’re using different contexts for `runBlocking` (you create a new one) and your view model. If you do `runBlocking(viewModel)` it might work

Hmm  .. I though that's how you're supposed to inject coroutineContexts so that you can have a different one for tests?

Well yeah, but you need to use the same context as the view model in `runBlocking`

Try extracting your `TestCoroutineContext` into a property and pass that to `runBlocking`

Bingo! `runBlocking(testCoroutineContext)` did the trick.

<@U3E6P7LPN> Did you try to pass `Dispatchers.Unconfined` instead of the `testCoroutineContext`?

In my real app there is no `delay` - instead our suspend function wraps an existing callback-based API. It looks like this solution of using the same context for `runBlocking` as in the `viewModel` is the right solution in that case

<@U3E6P7LPN> I’m a little surprised you need to use a `TestCoroutineContext` in your test-case instead of a plain `Dispatchers.Unconfined`…. I wrote the `TestCoroutineContext` class. The class is not very useful when you don’t need to call `triggerActions`, `advanceTimeBy` or `advanceTimeTo` on it.

I did try with `Dispatchers.Unconfined` but ran into some nullability exception. I guess if I spend some more time on it I can figure out how to use it too.

Hmmm… did you try `EmptyCoroutineContext`?

Hmm .. with `EmptyCoroutineContext` I also have the test failing. It doesn't make sense to me because the way I understand it - everything should work as long as the same coroutine context is shared

Exactly…!
Well, if `TestCoroutineContext` works, that’s great! :slightly_smiling_face:
I would love to know why, though. It probably has something to do with the internal Dispatcher of the TestCoroutineContext, but the Unconfined or EmptyCoroutineContext should have similar behavior…..

<@U72C3TBDH> thanks a bunch for looking into this. For now I've used `TestCoroutineContext` and updated the github repo. I'll leave it there in case anyone wants to take a look, or try to dig into ways to achieve it using `Unconfined` or `EmptyCorutineContext`