BufferedSender implements Sender { @Override public void addListener(SenderListener listener) { sender.addListener(listener); } BufferedSender(Builder builder);   BufferedSender(Builder builder, ScheduledExecutorService executorService); Queue<Payload> queue(); Sender sender(); @Override void send(Payload payload); @Override void addListener(SenderListener listener); @Override List<SenderListener> getListeners(); @Override void close(); @Override void close(boolean wait);  }
@Test public void shouldDelegateAddListener() { sut.addListener(listener); verify(sender).addListener(listener); }