Network Scheduling Simulation

    @Test
    public void networkRequestSchedulingSimulation() {
        BehaviorSubject<String> syncResultSubject = BehaviorSubject.create("L0");
        PublishSubject<Integer> syncRequestSubject = PublishSubject.create();

        Observable<Input> syncResultInputSubject = syncResultSubject.toObservable().map(new Func1<String, Input>() {
            @Override
            public Input call(String integer) {
                    return Input.RESULT;
            }
        });

        Observable<Input> syncRequestInputSubject = syncRequestSubject.toObservable().map(new Func1<Integer, Input>() {
            @Override
            public Input call(Integer integer) {
                return Input.SYNC;
            }
        });

        Observable<Input> merge = Observable.merge(syncRequestInputSubject, syncResultInputSubject);

        Observable<State> stateObservable = merge.scan(State.IDLE, new Func2<State, Input, State>() {
            @Override
            public State call(State currentState, Input input) {
                boolean isSyncRequest = input.equals(Input.SYNC);
                State nextState = currentState;
                switch (currentState) {
                    case IDLE:
                        nextState = isSyncRequest ? State.STARTED : State.IDLE;
                        break;
                    case STARTED:
                        nextState = isSyncRequest ? State.QUEUED : State.IDLE;
                        break;
                    case QUEUED:
                        nextState = isSyncRequest ? State.QUEUED : State.STARTED;
                        break;

                }
                return nextState;
            }
        });


        stateObservable.subscribe(observer);

        /*
result          |L0------L1--------L3--L4-----
sync request    |----S0----S1--S2----------S3--
merged signals  |L0--S0--L1S1--S2--L3--L4--S3--
states          |I---S---I-S---Q---S---I---S--
sync operation  |----O0----O1------02------O3--
         */

        syncRequestSubject.onNext(0);
        syncResultSubject.onNext("L1");
        syncRequestSubject.onNext(1);
        syncRequestSubject.onNext(2);
        syncResultSubject.onNext("L3");
        syncResultSubject.onNext("L4");
        syncRequestSubject.onNext(3);

        verify(observer, times(4)).onNext(State.STARTED);
        verify(observer, never()).onError(any(Throwable.class));
        verify(observer, never()).onCompleted();
        verifyNoMoreInteractions(observer);

    }