How can await util all messages was processed by actor in unit test?

Question

I'm using Akka actor in our product. We wrote some code:

   @Singleton
   public class SingletonObj {
      private Map<String, Integer> cached = new HashMap();
      public void set(String key, Integer value) {
         cached.put(key, value);
      }

      public void delete(String key){
         cached.delete(key}
      }
   }

   public class MyActor  extends AbstractActor implements InjectedActorSupport {
       @Inject SingletonObj singletonObj;

        public static Props props(Injector injector) {
        return Props.create(MyActor.class, injector);
    }

    public MyActor(Injector injector) {
        this.injector = injector;
        receive(ReceiveBuilder.create()
            .match(AddEvent.class, this::addEvent)
            .match(DeteteEvent.class, this::deleteEvent))
            .build());
        }
        private void addEvent(AddEvent addEvent) {singletonObj.set(addEvent.key, addEvent.value);}

        private void deteleEvent(DeteteEvent event){singletonObj.detele(event.key);}
   }

   public class Controller {

       private Injector injector;
       private ActorSystem actorSystem;

       public void handleAdd()...

       public void handleDelete()...


   }

Then when I wrote some test in junit for these class

   @Test public void testMethod(){
       sendAddRequest(...);
       sendDeteleRequest(...)
       ...
       ...

       assertThat(singletonObj.get("someString")).isEqual(42)
    }

Then this test is unreliable because when I do assertion, then all events was not handled yet.

How can I wait utils all events in actor system finish?

Answer 1

Import the below package and then you can await till you process all the events or the test will fail after timeout.

testCompile 'org.awaitility:awaitility:3.1.0'

import org.awaitility.Awaitility;

And before your assertThat use

await().pollInterval(5, TimeUnit.MILLISECONDS).until(() -> !isProcessed());

The isProcessed method will look something like below

protected Callable<Boolean> isProcessed() {
        return () -> {
            return singletonObj.getCacheCount()==2;
        };
    }

Regards,

Vinoth