public void When_receiving_unhandled_reminder()
            {
                var a = new TestDefaultActor();

                Assert.ThrowsAsync <UnhandledReminderException>(async() => await
                                                                a.OnReminder("test"));
            }
            public void When_receiving_unhandled_message()
            {
                var a = new TestDefaultActor();

                Assert.ThrowsAsync <UnhandledMessageException>(async() => await
                                                               a.OnReceive(new Y()), "Should throw by default");
            }