public void ToEventHandlerDetachTest()
    {
        var counter = 0;
        var command = new ReactiveCommand();

        command.Subscribe(_ => counter++);
        var b = new DummyButton();
        var h = command.ToEventHandler();

        b.Click += h;

        counter.Is(0);
        b.OnClick();
        counter.Is(1);

        b.Click -= h;
        b.OnClick();
        counter.Is(1);
    }
    public void ToEventHandlerTest()
    {
        var called  = false;
        var command = new ReactiveCommand();

        command.Subscribe(_ => called = true);
        var b = new DummyButton();

        b.Click += command.ToEventHandler();

        called.IsFalse();
        b.OnClick();
        called.IsTrue();
    }