    @Test
    public void testPut() {

        TestActorRef<MCacheDb> actorRef = TestActorRef.create(actorSystem, Props.create(MCacheDb.class));
        actorRef.tell(new SetRequest("key", "value"), ActorRef.noSender());

        MCacheDb mCacheDb = actorRef.underlyingActor();
        Assert.assertEquals(mCacheDb.getValue("key"), "value");
    }