idling.java

private void registerRxJavaIdlingResources() {
        RxIdlingResource rxIdlingResource = new RxIdlingResource();

        RxJavaHooks.setOnObservableStart((observable, onSubscribe) -> {
            rxIdlingResource.incrementActiveSubscriptionsCount();
            return onSubscribe;
        });

        RxJavaHooks.setOnObservableReturn(subscription -> {
            rxIdlingResource.decrementActiveSubscriptionsCount();
            return subscription;
        });

        RxJavaHooks.setOnObservableSubscribeError(throwable -> {
            rxIdlingResource.decrementActiveSubscriptionsCount();
            return throwable;
        });

        Espresso.registerIdlingResources(rxIdlingResource);
    }