def test_get_related_objects_selected_book_added_user(self):
        """
        This case is testing only 'added_book' param, because for
        user who is reading the book only this attribute will change relatively to function above.
        """
        third_book = Book.objects.get(book_name='Third Book')
        sixth_book = Book.objects.get(book_name='Sixth Book')

        self.assertTrue(isinstance(Book.get_related_objects_selected_book(self.the_user1.id_user, third_book.id), dict))

        related_third_book = Book.get_related_objects_selected_book(self.the_user1.id_user, third_book.id)
        related_sixth_book = Book.get_related_objects_selected_book(self.the_user1.id_user, sixth_book.id)

        self.assertEqual(related_third_book['added_book'],
                         AddedBook.objects.get(id_book=third_book, id_user=self.the_user1))
        self.assertEqual(related_sixth_book['added_book'],
                         AddedBook.objects.get(id_book=sixth_book, id_user=self.the_user1))