Campsite.java

/**
 * Classes
 */

import java.util.*;
import org.junit.*;
import org.junit.runner.*;

public class Solution {
    static class Item {
        String name;
        int expiry;
        int quality;

        public Item(String name, int expiry, int quality) {
            this.name = name;
            this.expiry = expiry;
            this.quality = quality;
        }
    }

    static class StoreInventory {
        List<Item> items;

        public StoreInventory(List<Item> items) {
            this.items = items;
        }

        public List<Item> updateQuality() {
            for (Item item : this.items) {
                if (item.name.equals("Instant Ramen")) {
                    // do nothing
                }

                if (item.name.equals("Cheddar Cheese")) {
                    if (item.quality < 25) {
                        item.quality += 1;
                    }
                    item.expiry -= 1;
                }

                if (!item.name.equals("Cheddar Cheese") && !item.name.equals("Instant Ramen")) {
                    item.expiry -= 1;
                    if (item.expiry > 0) {
                        if (item.quality > 0) {
                            item.quality -= 1;
                        }
                    }

                    if (item.expiry < 0) {
                        if (item.quality > 1) {
                            item.quality -= 2;
                        }
                        if (item.quality == 1) {
                          item.quality -= 1;
                        }
                    }
                }
            }
            return this.items;
        }
    }

/**
 * Implementation
 */

    public static void main(String[] args) {
        List<Item> items = new ArrayList<>();
        items.add(new Item("Apple", 10, 10));
        items.add(new Item("Banana", 7, 9));
        items.add(new Item("Strawberry", 5, 10));
        items.add(new Item("Cheddar Cheese", 10, 16));
        items.add(new Item("Instant Ramen", 0, 5));
        items.add(new Item("Organic Avocado", 5, 16));

        StoreInventory storeInventory = new StoreInventory(items);

        int days = 2;

        for (int i = 0; i < days; i++) {
            System.out.println("Day " + i + "  ---------------------------------");
            System.out.println("                  name      expiry quality");
            for (Item item : items) {
                System.out.println(item.name + " " + item.expiry + " " + item.quality);
            }
            System.out.println();
            storeInventory.updateQuality();
        }

        JUnitCore.main("Solution");
    }

/**
 * Tests
 */

    @Test
    public void shouldDecrementQualityDaily() {
        List<Item> testItems = Arrays.asList(new Item("test", 10, 10));
        StoreInventory testInventory = new StoreInventory(testItems);

        testInventory.updateQuality();
        Assert.assertEquals(9, testItems.get(0).quality);
    }

    @Test
    public void shouldIncrementCheddarCheeseQualityDaily() {
        List<Item> testItems = Arrays.asList(new Item("Cheddar Cheese", 10, 10));
        StoreInventory testInventory = new StoreInventory(testItems);

        testInventory.updateQuality();
        Assert.assertEquals(11, testItems.get(0).quality);
    }
}