public void RefreshWithFunc() { var num = 1; var d = new Drawing (new Size (50, 50), s => { for (var i = 0; i < num; i++) { s.DrawEllipse (new Point (10*i, 20), new Size (30, 40), Pens.Black); } }); Assert.AreEqual (1, d.Graphic.Children.Count); num = 2; d.Invalidate (); Assert.AreEqual (2, d.Graphic.Children.Count); }