Testing utility actor to mimic the messaging behavior of an actor a test might interact with, but without actually creating an instance of the actor

ParrotActor.java

package com.turbo.akka;

import akka.actor.UntypedActor;
import akka.event.Logging;
import akka.event.LoggingAdapter;

import java.util.HashMap;
import java.util.Map;

/**
 * Utility actor that is configured with a set of incoming messages types and response instances
 */
public class ParrotActor extends UntypedActor {
    private final LoggingAdapter LOG = Logging.getLogger(getContext().system(), this);

    /**
     * Init empty squawk map
     */
    public ParrotActor() {
        this.replyMap = new HashMap<Class, Object>();
    }

    /**
     * Init with pre-populated squawk map
     * @param replyMap
     */
    public ParrotActor(Map<Class, Object> replyMap) {
        this.replyMap = replyMap;
    }

    private final Map<Class, Object> replyMap;

    @Override
    public void onReceive(Object o) throws Exception {
        //check if we need to add a squawk
        if (o instanceof Squawk) {
            Squawk squawk = (Squawk) o;
            if (((Squawk) o).msg == null) {
                replyMap.remove(squawk.type);
                LOG.info("Removed Squawk for type : " + squawk.type);
            }
            else {
                replyMap.put(squawk.type, squawk.msg);
                LOG.info("Added new Squawk for type : " + squawk.type);
            }
            return;
        }

        //try to squawk
        Object reply = replyMap.get(o.getClass());
        if (reply != null) {
            sender().tell(reply, getSelf());
            LOG.info("Squawk! " + o.toString() + ". Sent: " + reply.toString());
            return;
        }
        unhandled(o);
    }

    /**
     * Pass this as a msg to ParrotActor to add a new squawk to list of
     * parroted messages
     */
    public static class Squawk {
        public final Class type;
        public final Object msg;

        public Squawk(Class type, Object msg) {
            this.type = type;
            this.msg = msg;
        }
    }
}