Arguments forwarding test

rxtest.kt

class RxTest {

    @Test fun forward() {
        fun <T : Any, R : Any> Observable<T>.forwardFlatMap(block: () -> Observable<R>): Observable<Pair<T, R>>
                = flatMap { item -> block().map { item to it } }

        Observable.just("")
                .flatMap { str ->
                    Observable.just(1)
                            .map { str to it }
                }
                .map { (x, y) -> "$x$y" }
                .test()
                .assertValue("1")

        Observable.just("")
                .forwardFlatMap { Observable.just(1) }
                .map { (x, y) -> "$x$y" }
                .test()
                .assertValue("1")
    }
}