### Question:
ForwardingClientStreamListener implements ClientStreamListener { @Override public void messagesAvailable(MessageProducer producer) { delegate().messagesAvailable(producer); }  @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 messagesAvailableTest() { MessageProducer producer = mock(MessageProducer.class); forward.messagesAvailable(producer); verify(mock).messagesAvailable(same(producer)); }