public class Rectangle

    {

        public virtual int Width { get; set; }

        public virtual int Height { get; set; }

        public Rectangle() { }

        public Rectangle(int width, int height)

        {

            this.Width = width;

            this.Height = height;

        }

        public virtual int Size

        {

            get

            {

                return this.Height * this.Width;

            }

        }

    }

  [TestMethod()]

        public void TestSize()

        {

            int expectedWidth = 3;

            int expectedHeight=7;

            Rectangle rectangle = new Rectangle(expectedWidth, expectedHeight);

            Assert.AreEqual(expectedWidth, rectangle.Width);

            Assert.AreEqual(expectedHeight, rectangle.Height);

        }

 public class Square : Rectangle

    {

        public Square() { }

        public Square(int width)

            : base(width, width)

        {

        }

        public override int Size

        {

            get

            {

                return this.Width * this.Width;

            }

        }

    }

[TestMethod()]

        public void TestSize()

        {

            int expectedWidth = 3;

            int expectedHeight=7;

            Rectangle square = new Square(expectedWidth);

            Assert.AreEqual(expectedWidth, square.Width);

            Assert.AreEqual(expectedHeight, square.Height);//fail

        }