public void the_different_books()
        {
            var book1 = PotterBooks.First(1);
            var book2 = PotterBooks.Second(1);

            book1.Should().NotBe(book2);
        }
        public void the_same_book()
        {
            var book1 = PotterBooks.First(1);
            var book2 = PotterBooks.First(2);

            book1.Should().Be(book2);
        }
 public void when_buy_two_the_same_series_books_then_amount_should_be_200()
 {
     BooksAmountShouldBe(
         books: new List <Book>
     {
         PotterBooks.First(2),
     },
         expected: 200m);
 }
 public void when_buy_a_book_then_amount_should_be_100()
 {
     BooksAmountShouldBe(
         books: new List <Book>
     {
         PotterBooks.First(1)
     },
         expected: 100m);
 }
 public void when_buy_two_the_same_series_books_and_one_different_series_book_then_amount_should_be_290()
 {
     BooksAmountShouldBe(
         books: new List <Book>
     {
         PotterBooks.First(2),
         PotterBooks.Second(1),
     },
         expected: 290m);
 }
 public void when_buy_two_different_series_books_then_amount_should_be_190()
 {
     BooksAmountShouldBe(
         books: new List <Book>
     {
         PotterBooks.First(1),
         PotterBooks.Second(1),
     },
         expected: 190m);
 }
 public void when_buy_four_different_series_books_then_amount_should_be_320()
 {
     BooksAmountShouldBe(
         books: new List <Book>
     {
         PotterBooks.First(1),
         PotterBooks.Second(1),
         PotterBooks.Third(1),
         PotterBooks.Fourth(1),
     },
         expected: 320m);
 }
 public void when_buy_five_different_series_books_and_three_different_series_books_then_amount_should_be_640()
 {
     BooksAmountShouldBe(
         books: new List <Book>
     {
         PotterBooks.First(2),
         PotterBooks.Second(2),
         PotterBooks.Third(2),
         PotterBooks.Fourth(1),
         PotterBooks.Fifth(1),
     },
         expected: 640m);
 }