RxJava 2 overriding IO scheduler in unit test

Question

I\'m trying to test the following RxKotlin/RxJava 2 code:

validate(data)
    .subscribeOn(Schedulers.io())
    .observeO         


        

Answer 1

Figured it out! It had to do with the fact that in this code:

validate(data)
    .subscribeOn(Schedulers.io())
    .observeOn(AndroidSchedulers.mainThread())
    .flatMap { ... }

validate(data) was returning an Observable, which was emitting the following: emitter.onNext(null). Since RxJava 2 no longer accepts null values, flatMap was not getting called. I changed validate to return a Completable and updated the scheduler override to the following:

RxJavaPlugins.setIoSchedulerHandler { Schedulers.trampoline() }

Now the tests pass!