def calculate_discount(self, basket: List[ShopItem]) -> Tuple[str, int]:
"""
Custom offer, this offer is: For every 2x soup in the basket, the shopper gets 50% off a loaf of bread
"""
soup_quantity = self.count_item_in_basket(basket, Soup)
bread_discount_max_quantity = int(soup_quantity / 2).__floor__()
bread_quantity = self.count_item_in_basket(basket, Bread)
# Get the number of bread we could apply discount on
discount_quantity = min(bread_quantity, bread_discount_max_quantity)
logger.debug(
f"Applying discount {self.name} to {discount_quantity} items")
bread_offer = PercentageOffer("Bread Offer if you buy Soup", Bread, 50,
discount_quantity)
_, discount = bread_offer.calculate_discount(basket)
logger.debug(
f"Offer {self.name}, total discount is {discount} on {discount_quantity} items"
)
message = (
f"Soup, Buy 2 and get 50% off a loaf of Bread: -{format_currency(discount)}"
if discount > 0 else None)
return message, discount
def test_apply_no_quantity_of_discount(self):
basket = [Apples(), Apples(), Apples(), Apples(), Bread(), Soup()]
percentage = 25
number_on_offer = 0
offer = PercentageOffer("Apple discount", Apples, percentage,
number_on_offer)
text, discount = offer.calculate_discount(basket)
self.assertEqual(0, discount)
self.assertEqual(None, text)
def test_apply_no_items(self):
basket = []
percentage = 10
offer = PercentageOffer("Apple discount", Apples, percentage)
text, discount = offer.calculate_discount(basket)
discount_per_apple = int(Apples().pence_price / percentage).__ceil__()
self.assertEqual(basket.count(Apples()) * discount_per_apple, discount)
self.assertEqual(None, text)
def test_apply_single_apple(self):
percentage = 10
offer = PercentageOffer("Apple discount", Apples, percentage)
basket = [Apples()]
text, discount = offer.calculate_discount(basket)
discount_per_apple = int(Apples().pence_price / percentage).__floor__()
self.assertEqual(discount_per_apple, discount)
self.assertEqual("Apples 10% off: -10p", text)
def test_apply_no_apples_other_items(self):
basket = [Bread(), Soup()]
percentage = 25
offer = PercentageOffer("Apple discount", Apples, percentage)
text, discount = offer.calculate_discount(basket)
discount_per_apple = self.discount_each(Apples().pence_price,
percentage)
self.assertEqual(basket.count(Apples) * discount_per_apple, discount)
self.assertEqual(None, text)
def test_apply_more_items_in_basket_than_discount(self):
basket = [Apples(), Apples(), Apples(), Apples(), Bread(), Soup()]
percentage = 25
number_on_offer = 2
offer = PercentageOffer("Apple discount", Apples, percentage,
number_on_offer)
text, discount = offer.calculate_discount(basket)
discount_per_apple = int(Apples().pence_price *
(percentage / 100)).__floor__()
self.assertEqual(discount_per_apple * number_on_offer, discount)
self.assertEqual(f"Apples {percentage}% off: -50p", text)
def test_apply_apples_and_other_items(self):
basket = [Apples(), Apples(), Apples(), Apples(), Bread(), Soup()]
percentage = 25
offer = PercentageOffer("Apple discount", Apples, percentage)
text, discount = offer.calculate_discount(basket)
discount_per_apple = int(Apples().pence_price *
(percentage / 100)).__floor__()
self.assertEqual(
self.count_items_of_type(basket, Apples) * discount_per_apple,
discount)
self.assertEqual(f"Apples {percentage}% off: -£1.00", text)
def test_apply_many_apples(self):
basket = [Apples(), Apples(), Apples(), Apples()]
percentage = 10.11
offer = PercentageOffer("Apple discount", Apples, percentage)
text, discount = offer.calculate_discount(basket)
discount_per_apple = self.discount_each(Apples().pence_price,
percentage)
self.assertEqual(
self.count_items_of_type(basket, Apples) * discount_per_apple,
discount)
self.assertEqual("Apples 10.11% off: -40p", text)
def setUp(self) -> None:
self.products = {
"apples": Apples,
"bread": Bread,
"soup": Soup,
"milk": Milk
}
self.offers = [
PercentageOffer("Apples, 10% off", Apples, 10),
SoupOffer("Buy 2 soup and get 50% off a loaf of bread"),
]
from goods.apples import Apples
from offers.percentage_offer import PercentageOffer
from offers.soup_offer import SoupOffer
# This week's offers
offers = [
PercentageOffer("Apples, 10% off", Apples, 10),
SoupOffer("Buy 2 soup and get 50% off a loaf of bread"),
]