public void Item_CheckOutValidation()
{
AdultBook a = new AdultBook();
ChildBook c = new ChildBook();
DVD d = new DVD();
VHS v = new VHS();
a.checkout("Tom");
c.checkout("Dick");
d.checkout("Harry");
v.checkout("Mickey");
Assert.AreEqual("Tom", a.whoCheckedOut);
Assert.AreEqual("Dick", c.whoCheckedOut);
Assert.AreEqual("Harry", d.whoCheckedOut);
Assert.AreEqual("Mickey", v.whoCheckedOut);
}