public void RemoveBook_NotExistingBook()
        {
            StringWriter output = new StringWriter();
            ModelStore model = ModelMockup();
            Viewer view = new Viewer(output);
            Controller control = new Controller(model, view);

            Customer c = model.GetCustomer(2);
            Book b = model.GetBook(2);

            try {
                control.RemoveBook(c, b);
                Assert.Fail("Expected exception was not thrown.");
            }
            catch(Exception ex) {
                Assert.AreEqual("Book doesn't exist in Customers ShoppingCart.", ex.Message);
            }
        }
        public void RemoveBook_DeleteBook()
        {
            StringWriter output = new StringWriter();
            ModelStore model = ModelMockup();
            Viewer view = new Viewer(output);
            Controller control = new Controller(model, view);

            Customer c = model.GetCustomer(2);
            Book b = model.GetBook(5);

            control.RemoveBook(c, b);

            Assert.AreEqual(model.GetCustomer(2).ShoppingCart.Items.Find(itm => itm.BookId == b.Id), null);
        }