public void RectExtensions2()
{
Rect a = new Rect(10, 20, 30, 40);
Assert.AreEqual(20, a.Add_X(10).x);
Assert.AreEqual(0, a.Add_X(-10).x);
Assert.AreEqual(40, a.Add_Y(20).y);
Assert.AreEqual(60, a.Add_Width(30).width);
Assert.AreEqual(80, a.Add_Height(40).height);
}
