JMock

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class Publisher {

    List<Subscriber> listener = new ArrayList<Subscriber>();

    public void publish(String message) {
        for (Iterator iterator = listener.iterator(); iterator.hasNext();) {
            Subscriber s = (Subscriber) iterator.next();
            s.receive(message);
        }
    }

    public void add(Subscriber subscriber) {
        listener.add(subscriber);
    }
}

 

 

interface Subscriber {
    void receive(String message);
}

 

 

 

import junit.framework.TestCase;

import org.jmock.Expectations;
import org.jmock.Mockery;

public class PublisherTest extends TestCase {
    Mockery context = new Mockery();

    public void testOneSubscriberReceivesAMessage() {
        // set up
        final Subscriber subscriber = context.mock(Subscriber.class);
        Publisher publisher = new Publisher();
        publisher.add(subscriber);
        
        final String message = "message";
        
        // expectations
        context.checking(new Expectations() {{
            oneOf (subscriber).receive(message);
        }});

        // execute
        publisher.publish(message);
        
        // verify
        context.assertIsSatisfied();
    }
}