Hand and scoring

src/blackjack/core.clj

@@ -33,15 +33,15 @@
 
 (defn play-hand [strategy hand opponent-up-card]
   (cond (> (total hand) 21)
-        hand
+          hand
 
         (strategy hand opponent-up-card) ; Asks 'should I hit?'
-        (recur strategy
-               (add-card hand (deal)) ; Recurs, adding a card
-               opponent-up-card)
+          (recur strategy
+                (add-card hand (deal)) ; Recurs, adding a card
+                opponent-up-card)
 
         :else
-        hand))
+          hand))
 
 (defn play-game [player-strategy house-strategy]
   (let [house-initial-hand (new-hand)

src/blackjack/hand.clj

@@ -27,8 +27,21 @@
   (conj hand card))
 
 (defn total [hand]
-  (reduce + (map (fn [{:keys [rank]}]
-                   (if (number? rank)
-                     rank
-                     10))
-                 hand)))
+  (defn ace? [card]
+    (= :A (:rank card)))
+  (defn score [{rank :rank}]
+    (if (number? rank)
+                  rank
+                  10))
+  (let [aces (filter ace? hand)
+        subtotal
+          (->> hand
+            (remove ace?)
+             (map score)
+             (reduce + 0))]
+    (reduce (fn [score _]
+              (if (> (+ score 11) 21)
+                (+ score 1)
+                (+ score 11)))
+            subtotal
+            aces)))

src/blackjack/simple_hand.clj

@@ -1,7 +1,7 @@
 (ns blackjack.simple-hand)
 
 (defn deal []
-  (inc (rand-int 10)))
+  {:rank (inc (rand-int 10))})
 
 (defn new-hand [] [(deal)])
 
@@ -12,4 +12,4 @@
   (conj hand card))
 
 (defn total [hand]
-  (reduce + hand))
+  (reduce + (map :rank hand)))

test/blackjack/hand_test.clj

@@ -13,3 +13,13 @@
     (testing "is 2 shuffled decks"
       (is (= (set two-decks)
              (set (concat full-deck full-deck)))))))
+
+(deftest test-hand-total
+  (testing "sums hand when just number cards"
+    (is (= 17 (total [{:rank 5} {:rank 2} {:rank 10}]))))
+  (testing "face cards are 10"
+    (is (= 30 (total [{:rank :J} {:rank :Q} {:rank :K}]))))
+  (testing "ace is 11 when hand is small"
+    (is (= 15 (total [{:rank :A} {:rank 4}]))))
+  (testing "ace is 1 when hand is large"
+    (is (= 21 (total [{:rank :K} {:rank :A} {:rank 10}])))))