Extended discard functionality

Extended the __init__ method and adjusted some other methods to allow the user to specify another Deck object to act as the discard pile.

Helpful if you want to be able to manipulate the discard pile without accessing the _discard_pile, whilst maintaining the functionality shuffle_back(), discarded, etc.

Also added a unit test for this new functionality.

pyCardDeck/deck.py

@@ -27,9 +27,11 @@ class Deck:
     :type reshuffle:    bool
     :param name:        Name of the deck, used when converting the Deck instance into string
     :type name:         string
+    :param discard:     optional Deck object to use as discard pile
+    :type discard:      Union[Deck, None]
     """
 
-    def __init__(self, cards: object = None, reshuffle: object = True, name: object = None):
+    def __init__(self, cards: object = None, reshuffle: object = True, name: object = None, discard: Union['Deck', None] = None):
         """
         Create the deck
         """
@@ -38,7 +40,10 @@ def __init__(self, cards: object = None, reshuffle: object = True, name: object
         self._cards = cards
         if self._cards is None:
             self._cards = []
-        self._discard_pile = []
+        if discard is None:
+            self._discard_pile = []
+        else:
+            self._discard_pile = discard
         self._reshuffle = reshuffle
         self._save_location = None
 
@@ -198,7 +203,10 @@ def shuffle_back(self) -> object:
         for card in self._discard_pile:
             self._cards.append(card)
         self.shuffle()
-        self._discard_pile = []
+        if isinstance(self._discard_pile, Deck):
+            self._discard_pile.clear()
+        else:
+            self._discard_pile = []
         log.debug('Cards have been shuffled back from the discard pile')
 
     def discard(self, card: CardType) -> None:
@@ -211,7 +219,10 @@ def discard(self, card: CardType) -> None:
         """
         log.debug("Card being discarded: %s", card)
         if card or type(card) == int:
-            self._discard_pile.append(card)
+            if isinstance(self._discard_pile, Deck):
+                self._discard_pile.add_single(card, 0)
+            else:
+                self._discard_pile.append(card)
             log.debug('Card %s discarded', card)
         # This had a reason, I remember testing something and ending
         # up with False/None in discard_pile - if anyone knows what

tests/test_deck.py

@@ -170,6 +170,23 @@ def test_discard():
     assert d.discarded == 3
 
 
+def test_deck_discard():
+    cardlist = [
+        Card('One'), Card('Two'), Card('Three'), Card('Four')
+    ]
+    discardpile = Deck(reshuffle=False)
+    d = Deck(cards=cardlist[:], reshuffle=False, discard=discardpile)
+    d.discard(d.draw())
+    d.discard(d.draw())
+    assert d.discarded == 2
+    assert len(discardpile) == 2
+    assert discardpile[1] == cardlist[0]
+    d.shuffle_back()
+    assert d.discarded == 0
+    assert len(d) == 4
+    assert len(discardpile) == 0
+
+
 def test_shuffle_back():
     d = Deck(cards=[
         Card('One'), Card('Two'), Card('Three'), Card('Four')