### Question:
ForwardingClientStreamListener implements ClientStreamListener { @Override public void closed(Status status, Metadata trailers) { delegate().closed(status, trailers); }  @Override void headersRead(Metadata headers); @Override void closed(Status status, Metadata trailers); @Override void closed(Status status, RpcProgress rpcProgress, Metadata trailers); @Override void messagesAvailable(MessageProducer producer); @Override void onReady(); @Override String toString();  }### Answer:
@Test public void closedTest() { Status status = Status.UNKNOWN; Metadata trailers = new Metadata(); forward.closed(status, trailers); verify(mock).closed(same(status), same(trailers)); }