Add Remove() method to remove a card from a deck. Add unit tests for …

…Remove and for Copy.

deck.go

@@ -22,6 +22,7 @@ func NewDeck() *Deck {
 	return deck
 }
 
+// Copy returns a copy of the deck.
 func (deck *Deck) Copy() *Deck {
 	if deck == nil {
 		return nil
@@ -33,6 +34,15 @@ func (deck *Deck) Copy() *Deck {
 	return deck2
 }
 
+// Remove removes a given card from the deck.
+func (deck *Deck) Remove(c Card) {
+	for i, c2 := range deck.cards {
+		if c == c2 {
+			deck.cards = append(deck.cards[:i], deck.cards[i+1:]...)
+		}
+	}
+}
+
 func (deck *Deck) Shuffle() {
 	deck.cards = make([]Card, len(fullDeck.cards))
 	copy(deck.cards, fullDeck.cards)

deck_test.go

@@ -19,6 +19,21 @@ func TestNewDeck(t *testing.T) {
 	assert.False(t, same)
 }
 
+func TestCopy(t *testing.T) {
+	deck := NewDeck()
+	deck2 := deck.Copy()
+	assert.NotSame(t, deck, deck2)
+	assert.EqualValues(t, deck, deck2)
+}
+
+func TestRemove(t *testing.T) {
+	deck := NewDeck()
+	c := NewCard("As")
+	assert.Contains(t, deck.cards, c)
+	deck.Remove(c)
+	assert.NotContains(t, deck.cards, c)
+}
+
 func TestDraw(t *testing.T) {
 	deck := NewDeck()