Akka actor that takes another ActorRef as a constructor argument, and forwards all incoming messages to the one passed in. This is useful for unit tests, where you can pass in a JavaTestKit instance to the constructor and all messages passed to this actor will be forwarded to the JavaTestKit instance.

ForwarderActor.java

package com.turbo.akka;

import akka.actor.ActorRef;
import akka.actor.UntypedActor;

 /**
 * Simple actor that takes another actor and forwards all messages to it.
 * Useful in unit testing for capturing and testing if a message was received. 
 * Simply pass in an Akka JavaTestKit probe into the constructor, and all messages 
 * that are sent to this actor are forwarded to the JavaTestKit probe
 */
public class ForwarderActor extends UntypedActor {
    final ActorRef target;
    public ForwarderActor(ActorRef target) {
        this.target = target;
    }
    public void onReceive(Object msg) {
        target.forward(msg, getContext());
    }
}