ObservableToSingle_assertObservableToSingle.kt

private fun assertObservableToSingle(
    sourceObservable: Observable<Int>,
    toSingleTransformation: Observable<Int>.() -> Single<Int>,
    assertions: TestObserver<Int>.() -> Unit
) {

    val connectableObservable : ConnectableObservable<Int> = sourceObservable
        .doOnNext { println("Source observable emitting $it") }
        .doOnError { println("Source observable emitted an error: $it") }
        .publish()

    val testObserver = connectableObservable.toSingleTransformation()
        .doOnSuccess { println("Single succeeded with value: $it") }
        .doOnError { println("Single emitted an error: $it") }
        .test()

    connectableObservable.connect()
    testObserver.await().assertions()
}