### Question:
MessageBrokerClient extends Client { public void sendMessageToTopic(Cdr message, Optional<String> topicName) throws EtiqetException { getTransport().sendToTopic(message, topicName); } MessageBrokerClient(String clientConfig);  MessageBrokerClient(String primaryClientConfig, String secondaryClientConfig);  MessageBrokerClient(String primaryClientConfig, String secondaryClientConfig, ProtocolConfig protocol); @Override boolean isLoggedOn(); void subscribeToTopic(String topicName); void subscribeToQueue(String queueName); void sendMessageToTopic(Cdr message, Optional<String> topicName); void sendMessageToQueue(Cdr message, String queueName); Cdr waitForMsgOnTopic(Optional<String> topic, int milliseconds); Cdr waitForMsgOnQueue(String queueName, int milliseconds); List<Cdr> getReceivedMessagesFromTopic(String topicName); List<Cdr> getReceivedMessagesFromQueue(String queueName); Optional<Cdr> getLastMessageFromTopic(String topicName); Optional<Cdr> getLastMessageFromQueue(String queueName); void clearQueue(String queueName); @Override BrokerTransport getTransport();  }### Answer:
@Test public void testSendMessageToTopic() throws Exception { Cdr cdr = new Cdr("NONE"); messageBrokerClient.sendMessageToTopic(cdr, empty()); verify(transport, times(1)).sendToTopic(cdr, empty()); }