public void TestSellError()
        {
            //Arrange
            Player    p1 = new Player(100);
            Player    p2 = new Player(100);
            RealState r  = new RealState(50, 5, owner: p1);

            //Act


            //Assert
            Assert.Throws <RealState.SellException>(() => r.SellTo(p2));
        }
        public void TestSell()
        {
            //Arrange
            Player    p = new Player(100);
            RealState r = new RealState(50, 5);

            //Act
            r.SellTo(p);

            //Assert
            Assert.IsTrue(r.HasOwner());
            Assert.IsTrue(r.OwnerIs(p));
            Assert.AreEqual(50, p.Balance);
        }