public void setAccount_AccountIsUpdated()
        {
            cc.SetAccount(new Account());
            FieldInfo fi     = typeof(CreditCard).GetField("_account", BindingFlags.Instance | BindingFlags.NonPublic);
            var       actual = fi.GetValue(cc);

            // does the variable contain an account object
            Assert.That(actual, Is.InstanceOf(typeof(Account)));
        }