Implement unit tests for Blackjack Java

10_Blackjack/java/src/Card.java

@@ -23,6 +23,12 @@ public final class Card {
 	private final Suit suit;
 
 	public Card(int value, Suit suit) {
+        if(value < 1 || value > 13) {
+            throw new IllegalArgumentException("Invalid card value " + value);
+        }
+        if(suit == null) {
+            throw new IllegalArgumentException("Card suit must be non-null");
+        }
 		this.value = value;
 		this.suit = suit;
 	}
@@ -51,4 +57,29 @@ public final class Card {
         // result.append(suit.name().charAt(0));
         return result.toString();
     }
+
+    @Override
+    public boolean equals(Object obj) {
+        // Overriding 'equals' and 'hashCode' (below) make your class work correctly
+        // with all sorts of methods in the Java API that need to determine the uniqueness
+        // of an instance (like a Set).
+        if(obj.getClass() != Card.class) {
+            return false;
+        }
+        Card other = (Card) obj;
+        return this.getSuit() == other.getSuit() && this.getValue() == other.getValue();
+    }
+
+    @Override
+    public int hashCode() {
+        // This is a fairly standard hashCode implementation for a data object.
+        // The details are beyond the scope of this comment, but most IDEs can generate
+        // this for you.
+
+        // Note that it's a best practice to implement hashCode whenever you implement equals and vice versa.
+        int hash = 7;
+        hash = 31 * hash + (int) value;
+        hash = 31 * hash + suit.hashCode();
+        return hash;
+    }
 }

10_Blackjack/java/src/Deck.java

@@ -1,8 +1,10 @@
+import java.util.Collections;
 import java.util.LinkedList;
+import java.util.List;
 
 public class Deck {
 
-    LinkedList<Card> cards;
+    private LinkedList<Card> cards;
     
     /**
      * Initialize the game deck with the given number of standard decks.
@@ -12,12 +14,14 @@ public class Deck {
      * @param nDecks
      */
     public Deck(int nDecks) {
-        // TODO implement Deck constructor
-        // See line 33 of Blackjack.java for the current version of this code
-        /* for each suit
-         *   for each value 1-13
-         *     add new Card(value, suit) to cards
-         */
+        cards = new LinkedList<>();
+        for(int deckIndex = 0; deckIndex < nDecks; deckIndex++) {
+            for(Card.Suit suit : Card.Suit.values()) {
+                for(int value = 1; value < 14; value++) {
+                    cards.add(new Card(value, suit));
+                }
+            }
+        }
     }
 
     /**
@@ -37,5 +41,20 @@ public class Deck {
         // Probably just call Collections.shuffle(cards);
     }
 
+    /**
+     * Get the number of cards in this deck.
+     * @return The number of cards in this deck. For example, 52 for a single deck.
+     */
+    public int size() {
+        return cards.size();
+    }
 
+    /**
+     * Returns the cards in this deck.
+     * @return An immutable view of the cards in this deck.
+     */
+    public List<Card> getCards() {
+        // The returned list is immutable because we don't want other code messing with the deck.
+        return Collections.unmodifiableList(cards);
+    }
 }

10_Blackjack/java/test/DeckTest.java

@@ -0,0 +1,40 @@
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertAll;
+import org.junit.jupiter.api.Test;
+
+public class DeckTest {
+
+    @Test
+    void testInitOne() {
+        // When
+        Deck deck = new Deck(1);
+
+        // Then
+        long nCards = deck.size();
+        long nSuits = deck.getCards().stream()
+                .map(card -> card.getSuit())
+                .distinct()
+                .count();
+        long nValues = deck.getCards().stream()
+                .map(card -> card.getValue())
+                .distinct()
+                .count();
+
+        assertAll("deck",
+            () -> assertEquals(52, nCards, "Expected 52 cards in a deck, but got " + nCards),
+            () -> assertEquals(4, nSuits, "Expected 4 suits, but got " + nSuits),
+            () -> assertEquals(13, nValues, "Expected 13 values, but got " + nValues)
+        );
+        
+    }
+
+    @Test
+    void testInitTwo() {
+        // When
+        Deck deck = new Deck(2);
+
+        // Then
+        assertEquals(104, deck.size());
+    }
+    
+}