public void RemoveOneItemNotPresent() { MessageBus bus = new MessageBus(); List <string> output = new List <string>(); Action <OutputMessage> subscriber = m => output.Add(m.Text); bus.Subscribe(subscriber); TestRoom room = new TestRoom(bus); Item removed = room.Remove("key"); room.Enter(); output.Should().Equal( "You are in a test room."); removed.Should().BeNull(); }