### Question:
ServiceImpl implements Service { @Override public Flux<String> doStaff() { return serviceA .cast(IServiceA.class) .flatMapMany(IServiceA::sourceA) .concatWith(serviceB.flatMapMany(IServiceB::sourceB)); }  @Override Flux<String> doStaff();  }### Answer:
@Test public void doStaff() { Service proxy = Injector.proxy(new ServiceImpl(), Service.class); StepVerifier.create(proxy.doStaff()) .expectSubscription() .expectAccessibleContext().hasKey(Injector.HOLDER_KEY).then() .expectNextCount(15) .verifyComplete(); }