Android Espresso not synchronized with Rx Completable

Issue

I have an issue with Espresso not waiting for Completable to finish, so my UI test is Failing

apiDataSource.getData()
             .flatMap { data ->
                    cacheDataSource.saveData(data)
                    .andThen(Observable.just(cacheDataSource.getData()))

is there a way to hold the Espresso thread until having the cacheDataSource.saveData(data) complete? Thank you in advance

Solution

The reason is that you call cacheDataSource.getData() right when you assemble the save sequence inside flatMap. From the documentation of just:

Note that the item is taken and re-emitted as is and not computed by any means by just. Use fromCallable(Callable) to generate a single item on demand (when Observers subscribe to it).

apiDataSource.getData()
         .flatMap { data ->
                cacheDataSource.saveData(data)
                .andThen(Observable.fromCallable { cacheDataSource.getData() })
         }

Answered By - akarnokd