public MainWindow(MainWindowViewModel viewModel)
        {
            InitializeComponent();

            ViewModel = viewModel;
            DataContext = ViewModel;
        }
        public void TestExitCommand()
        {
            var window = new Mock<IBaseWindow>();
            window.Setup(w => w.Close());

            var vm = new MainWindowViewModel(new RandomPointGenerator());
            vm.ExitCommand.Execute(window.Object);

            window.Verify(w => w.Close(), Times.Once);
        }