### Question:
AsyncRpcSender implements RpcSender { @Override public void attach(OutputStream outputStream) { Objects.requireNonNull(outputStream, "outputStream may not be null"); log.info("Attached to output stream!"); this.outgoingStream = outputStream; } AsyncRpcSender(ExecutorService executorService, ObjectMapper msgPacker); @Override void send(Message message); @Override void attach(OutputStream outputStream); @Override void stop();  }### Answer:
@Test public void testAttach() { asyncRpcSender.attach(outputStream); }