public void TestMessagePopupWhenPopupActivateMessageSentThenMessagePopupActivated() { //Assign MessagePopupViewModel viewModel = new MessagePopupViewModel(); var messageContent = new PopupActivateArgs(new AddScoreCommand(new CommandResultViewModel("aaa")), 0); bool prevActive = viewModel.IsActive; //Act Messenger.Default.Send(new PopupActivateMessage(messageContent)); //Assert Assert.True(!prevActive); Assert.True(viewModel.IsActive); }