Code To test internal generic methods with user code in them

How does one test this code

 public String SendMessage(String request) throws JMSException {

   TextMessage reply = (TextMessage) jmsTemplate.execute(new ProducerCallback() {
    public Object doInJms(Session session,MessageProducer producer) throws JMSException {
     TemporaryQueue queue = session.createTemporaryQueue();
     TextMessage message = session.createTextMessage();
     message.setText("Some Text");
     message.setJMSReplyTo(queue);
     producer.send(message);
     return session.createConsumer(queue).receive(10000);
    }
   });

   if (reply != null){
   // System.err.println("Message recieved");
   } else{
   // System.err.println("*** NOT received");
   }
   
   return reply.getText();

 }

here is my junit mockito 1.8 test

import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageProducer;
import javax.jms.TemporaryQueue;
import javax.jms.TextMessage;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;

import static org.mockito.Mockito.*;
import org.springframework.jms.core.JmsTemplate;
import org.springframework.jms.core.ProducerCallback;

import com.sun.messaging.jms.Session;

public class PrivateMessageSenderTest {

   PrivateMessageSender classUnderTest;
   JmsTemplate mockJmsTemplate;
   Session mockSession;
   MessageProducer mockMessageProducer;
   TemporaryQueue mockTemporaryQueue;
   TextMessage mockTextMessage;
   @Before
   public void setUp() throws Exception {
       classUnderTest = new OpenMQPrivateMessageSender();
     
       mockJmsTemplate = mock(JmsTemplate.class);
       mockSession = mock(Session.class);
       mockMessageProducer = mock(MessageProducer.class);
       mockTemporaryQueue = mock(TemporaryQueue.class);
       mockTextMessage = mock(TextMessage.class);
     
       /** Boiler plate mock code to inject mock session and messageProducer into
        *  Generic Spring ProducerCallback class which has our internal code
        *  To test
       **/
       when(mockJmsTemplate.execute((ProducerCallback)anyObject())).thenAnswer(
               new Answer

its missing the tests for it, but this pretty much sets it up to set mocks into the internal method.