public void TestAllArea()
{
Box box = new Box();
Material Paper = new Paper(50, 50);
Material Film = new Film(50, 50);
Paper = gurl.CutRectangle(Paper);
box.Add(Paper);
Paper = gurl.CutRectangle(Paper);
box.Add(Paper);
double expected = 49 * 49 + 48 * 48;
double actual = box.AllArea();
Assert.AreEqual(expected, actual);
}