Invalid values now return none

Author: Bernardo-MG

dice_notation/dice.py

@@ -127,8 +127,12 @@ def __init__(self, quantity, sides):
     def roll(self):
         result = 0
 
-        if self.quantity and self.sides and self.sides > 0:
+        if self.quantity == 0 or self.sides == 0:
+            result = 0
+        elif self.quantity > 0 and self.sides > 0:
             for x in xrange(self.quantity):
                 result += randint(1, self.sides)
+        else:
+            result = None
 
         return result

tests/test_dice.py

@@ -110,28 +110,28 @@ def test_negativeQuantity(self):
         """
         dice = RollableDice(-1, 1)
 
-        self.assertEqual(0, dice.roll())
+        self.assertIsNone(dice.roll())
 
     def test_negativeSides(self):
         """
         Tests that quantity of dice is multiplied by the sides when rolling.
         """
         dice = RollableDice(1, -1)
 
-        self.assertEqual(0, dice.roll())
+        self.assertIsNone(dice.roll())
 
     def test_noneQuantity(self):
         """
         Tests that quantity of dice is multiplied by the sides when rolling.
         """
         dice = RollableDice(None, 1)
 
-        self.assertEqual(0, dice.roll())
+        self.assertIsNone(dice.roll())
 
     def test_noneSides(self):
         """
         Tests that quantity of dice is multiplied by the sides when rolling.
         """
         dice = RollableDice(1, None)
 
-        self.assertEqual(0, dice.roll())
+        self.assertIsNone(dice.roll())