gilded_rose.py

from typing import List


class Item:
    name: str
    degradation: int = 1
    quality_min: int = 0
    quality_max: int = 50

    def __init__(self, name: str, sell_in: int, quality: int):
        assert quality >= self.quality_min
        assert quality <= self.quality_max

        self.name = name
        self.sell_in = sell_in
        self.quality = quality

    def next_day(self):
        self.sell_in -= 1

        diff = self.degradation
        if self.sell_in < 0:
            diff *= 2

        self.quality = self.quality - diff
        self.quality = max(self.quality_min, self.quality)
        self.quality = min(self.quality_max, self.quality)


class AgedBrie(Item):
    degradation = -1

    def __init__(self, sell_in: int, quality: int):
        super().__init__("Aged Brie", sell_in, quality)


class Conjured(Item):
    degradation = 2


class Sulfuras(Item):
    degradation = 0
    quality_min = 80
    quality_max = 80

    def __init__(self):
        super().__init__("Sulfuras, Hand of Ragnaros", sell_in=0, quality=80)

    def next_day(self):
        super().next_day()
        self.sell_in = 0


class Tickets(Item):
    def next_day(self):
        if self.sell_in <= 0:
            self.quality = 0
            self.sell_in -= 1
            return

        if self.sell_in <= 5:
            self.degradation = -3
        elif self.sell_in <= 10:
            self.degradation = -2
        else:
            self.degradation = -1

        super().next_day()


class GildedRose(object):
    items: List[Item]

    def __init__(self, items):
        self.items = items

    def update_quality(self):
        for item in self.items:
            item.next_day()

test_gilded_rose.py

import pytest
from gilded_rose import AgedBrie, Conjured, Sulfuras, Tickets
from collections import namedtuple

ItemValues = namedtuple("ItemValues", ["sell_in", "quality"])


@pytest.mark.parametrize(
    "item,expected_values",
    [
        [
            Sulfuras(),
            [
                ItemValues(sell_in=0, quality=80),
                ItemValues(sell_in=0, quality=80),
                ItemValues(sell_in=0, quality=80),
                ItemValues(sell_in=0, quality=80),
            ],
        ],
        [
            AgedBrie(sell_in=2, quality=0),
            [
                ItemValues(sell_in=2, quality=0),
                ItemValues(sell_in=1, quality=1),
                ItemValues(sell_in=0, quality=2),
                ItemValues(sell_in=-1, quality=4),
                ItemValues(sell_in=-2, quality=6),
            ],
        ],
        [
            Tickets(
                "Backstage passes to a TAFKAL80ETC concert", sell_in=15, quality=20
            ),
            [
                ItemValues(sell_in=15, quality=20),
                ItemValues(sell_in=14, quality=21),
                ItemValues(sell_in=13, quality=22),
                ItemValues(sell_in=12, quality=23),
                ItemValues(sell_in=11, quality=24),
                ItemValues(sell_in=10, quality=25),
                ItemValues(sell_in=9, quality=27),
                ItemValues(sell_in=8, quality=29),
                ItemValues(sell_in=7, quality=31),
                ItemValues(sell_in=6, quality=33),
                ItemValues(sell_in=5, quality=35),
                ItemValues(sell_in=4, quality=38),
                ItemValues(sell_in=3, quality=41),
                ItemValues(sell_in=2, quality=44),
                ItemValues(sell_in=1, quality=47),
                ItemValues(sell_in=0, quality=50),
                ItemValues(sell_in=-1, quality=0),
            ],
        ],
        [
            Conjured("Conjured Mana Potion", sell_in=2, quality=20),
            [
                ItemValues(sell_in=2, quality=20),
                ItemValues(sell_in=1, quality=18),
                ItemValues(sell_in=0, quality=16),
                ItemValues(sell_in=-1, quality=12),
                ItemValues(sell_in=-2, quality=8),
            ],
        ],
    ],
)
def test_items(item, expected_values):
    for values in expected_values:
        assert item.quality == values.quality
        assert item.sell_in == values.sell_in
        item.next_day()