How to unittest subscriber code?

[zsmeier]

Hi everybody,
we started to use the reactive rest client in our Quarkus project and i have some problems writing unit test for the code. Is there any nice way to test the code from the transform and from the subscribe part of the stream? i.e:

fun saveClientDataToDB() {
    reactiveRestClient.getData("someId")
        .onItem().transform { responseData ->
            transformResonse(responseData)
        }.subscribe().with { transformedResponse ->
            repository.persist(transformedResponse)
        }
}

I would like to write a unit-test, which checks if the data received with the rest client is transformed and it is persisted to the database.
In a non-reactive way, i would mock the reactiveRestClient and the repository, and verify if the persist method of the repository is called with a capture parameter to check the transformedData.

Is there any way to do this (without having Thread.sleep(1000) in the unit-test), or this is a basic thing and i'm missing something?

Any help is appreciated. Thx.
Zs.

[jponge]

I'd do an integration test for that, because you have a database and HTTP client call involved.

[zsmeier]

Hi Julian, thank you for your answer.
I think, even with an integration test, i would have the same problem. The test will finish before the rest call and the db persist is done, so I would still need a Thread.sleep().
At the end, in that case, i would say, the problem is, how to unit test an asynchronous method. I was wondering, if there is any "mutiny" way for it. If not, i think I will use something like the awaitility library (which is "just" a nice way for the Thread.sleep()).

[jponge]

If you want to test pipelines and need to deterministically await certain parts then yes Awaitility is a good idea 👍