Gilded Rose - From C# to Clojure

core.clj

(ns gildedrose.core)

(def DEXTERY_VEST "+5 Dexterity Vest")
(def AGED_BRIE "Aged Brie")
(def ELIXIR "Elixir of the Mongoose")
(def SULFURAS "Sulfuras, Hand of Ragnaros")
(def BACKSTAGE_PASSES "Backstage passes to a TAFKAL80ETC concert")
(def CONJURED "Conjured Mana Cake")

(def items [{:name DEXTERY_VEST :quality 20 :sell-in 10}
            {:name AGED_BRIE :quality 0 :sell-in 2}
            {:name ELIXIR :quality 7 :sell-in 5}
            {:name SULFURAS :quality 80 :sell-in 0}
            {:name BACKSTAGE_PASSES :quality 20 :sell-in 15}
            {:name CONJURED :quality 6 :sell-in 3}])

(defn default-quality-delta [sell-in]
  (if (pos? sell-in) 1 2))

(defmulti update-item :name)

(defmethod update-item :default [{:keys [name quality sell-in]}]
  {:name name
   :quality (max 0 (- quality (default-quality-delta sell-in)))
   :sell-in (dec sell-in)})

(defmethod update-item AGED_BRIE [{:keys [name quality sell-in]}]
  {:name name
   :quality (min 50 (+ quality (default-quality-delta sell-in)))
   :sell-in (dec sell-in)})

(defmethod update-item SULFURAS [item]
  item)

(defmethod update-item BACKSTAGE_PASSES [{:keys [name quality sell-in]}]
  (let [qdelta (cond
                 (<= sell-in 5) 3
                 (<= sell-in 10) 2
                 :else 1)]
    {:name name
     :quality (min 50 (if (pos? sell-in) (+ quality qdelta) 0))
     :sell-in (dec sell-in)}))

(defmethod update-item CONJURED [{:keys [name quality sell-in]}]
  {:name name
   :quality (max 0 (- quality (* 2 (default-quality-delta sell-in))))
   :sell-in (dec sell-in)})

(defn update-items [items]
  (map update-item items))

core_test.clj

(ns gildedrose.core-test
  (:require [clojure.test :refer :all]
            [gildedrose.core :refer :all]
            [gildedrose.core-test-approved :as approved]))

(deftest approval
  (testing "Original data - excluding conjured items"
    (let [updates (iterate update-items items)]
      (doall (map #(is (= (butlast %1) (butlast %2))) updates approved/data)))))

(deftest conjured-items
  (testing "Conjured items degrade twice as fast"
    (let [conjured {:name CONJURED :quality 5 :sell-in 10}]
      (is (= 3 (:quality (update-item conjured)))))
    (let [conjured {:name CONJURED :quality 5 :sell-in 0}]
      (is (= 1 (:quality (update-item conjured)))))
    (let [conjured {:name CONJURED :quality 5 :sell-in -1}]
      (is (= 1 (:quality (update-item conjured)))))))

core_test_approved.clj

(ns gildedrose.core-test-approved
  (:require  [clojure.test :as t]))

(def data [[{:name "+5 Dexterity Vest" :quality 20 :sell-in 10}
            {:name "Aged Brie" :quality 0 :sell-in 2}
            {:name "Elixir of the Mongoose" :quality 7 :sell-in 5}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 20 :sell-in 15}
            {:name "Conjured Mana Cake" :quality 6 :sell-in 3}]
           [{:name "+5 Dexterity Vest" :quality 19 :sell-in 9}
            {:name "Aged Brie" :quality 1 :sell-in 1}
            {:name "Elixir of the Mongoose" :quality 6 :sell-in 4}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 21 :sell-in 14}
            {:name "Conjured Mana Cake" :quality 5 :sell-in 2}]
           [{:name "+5 Dexterity Vest" :quality 18 :sell-in 8}
            {:name "Aged Brie" :quality 2 :sell-in 0}
            {:name "Elixir of the Mongoose" :quality 5 :sell-in 3}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 22 :sell-in 13}
            {:name "Conjured Mana Cake" :quality 4 :sell-in 1}]
           [{:name "+5 Dexterity Vest" :quality 17 :sell-in 7}
            {:name "Aged Brie" :quality 4 :sell-in -1}
            {:name "Elixir of the Mongoose" :quality 4 :sell-in 2}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 23 :sell-in 12}
            {:name "Conjured Mana Cake" :quality 3 :sell-in 0}]
           [{:name "+5 Dexterity Vest" :quality 16 :sell-in 6}
            {:name "Aged Brie" :quality 6 :sell-in -2}
            {:name "Elixir of the Mongoose" :quality 3 :sell-in 1}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 24 :sell-in 11}
            {:name "Conjured Mana Cake" :quality 1 :sell-in -1}]
           [{:name "+5 Dexterity Vest" :quality 15 :sell-in 5}
            {:name "Aged Brie" :quality 8 :sell-in -3}
            {:name "Elixir of the Mongoose" :quality 2 :sell-in 0}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 25 :sell-in 10}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -2}]
           [{:name "+5 Dexterity Vest" :quality 14 :sell-in 4}
            {:name "Aged Brie" :quality 10 :sell-in -4}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -1}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 27 :sell-in 9}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -3}]
           [{:name "+5 Dexterity Vest" :quality 13 :sell-in 3}
            {:name "Aged Brie" :quality 12 :sell-in -5}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -2}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 29 :sell-in 8}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -4}]
           [{:name "+5 Dexterity Vest" :quality 12 :sell-in 2}
            {:name "Aged Brie" :quality 14 :sell-in -6}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -3}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 31 :sell-in 7}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -5}]
           [{:name "+5 Dexterity Vest" :quality 11 :sell-in 1}
            {:name "Aged Brie" :quality 16 :sell-in -7}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -4}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 33 :sell-in 6}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -6}]
           [{:name "+5 Dexterity Vest" :quality 10 :sell-in 0}
            {:name "Aged Brie" :quality 18 :sell-in -8}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -5}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 35 :sell-in 5}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -7}]
           [{:name "+5 Dexterity Vest" :quality 8 :sell-in -1}
            {:name "Aged Brie" :quality 20 :sell-in -9}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -6}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 38 :sell-in 4}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -8}]
           [{:name "+5 Dexterity Vest" :quality 6 :sell-in -2}
            {:name "Aged Brie" :quality 22 :sell-in -10}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -7}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 41 :sell-in 3}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -9}]
           [{:name "+5 Dexterity Vest" :quality 4 :sell-in -3}
            {:name "Aged Brie" :quality 24 :sell-in -11}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -8}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 44 :sell-in 2}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -10}]
           [{:name "+5 Dexterity Vest" :quality 2 :sell-in -4}
            {:name "Aged Brie" :quality 26 :sell-in -12}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -9}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 47 :sell-in 1}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -11}]
           [{:name "+5 Dexterity Vest" :quality 0 :sell-in -5}
            {:name "Aged Brie" :quality 28 :sell-in -13}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -10}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 50 :sell-in 0}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -12}]
           [{:name "+5 Dexterity Vest" :quality 0 :sell-in -6}
            {:name "Aged Brie" :quality 30 :sell-in -14}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -11}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 0 :sell-in -1}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -13}]
           [{:name "+5 Dexterity Vest" :quality 0 :sell-in -7}
            {:name "Aged Brie" :quality 32 :sell-in -15}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -12}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 0 :sell-in -2}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -14}]
           [{:name "+5 Dexterity Vest" :quality 0 :sell-in -8}
            {:name "Aged Brie" :quality 34 :sell-in -16}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -13}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 0 :sell-in -3}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -15}]
           [{:name "+5 Dexterity Vest" :quality 0 :sell-in -9}
            {:name "Aged Brie" :quality 36 :sell-in -17}
            {:name "Elixir of the Mongoose" :quality 0 :sell-in -14}
            {:name "Sulfuras, Hand of Ragnaros" :quality 80 :sell-in 0}
            {:name "Backstage passes to a TAFKAL80ETC concert" :quality 0 :sell-in -4}
            {:name "Conjured Mana Cake" :quality 0 :sell-in -16}]])