FIX: #132

textworld/generator/game.py

@@ -803,6 +803,11 @@ def winning_policy(self) -> Optional[List[Action]]:
 
         return min(winning_policies, key=lambda policy: len(policy))
 
+    @property
+    def completable(self) -> bool:
+        """ Check if the quest has winning events. """
+        return len(self.win_events) > 0
+
     @property
     def done(self) -> bool:
         """ Check if the quest is done (i.e. completed, failed or unfinishable). """
@@ -872,7 +877,7 @@ def completed(self) -> bool:
         if not self.tracking_quests:
             return False  # There is nothing to be "completed".
 
-        return all(qp.completed for qp in self.quest_progressions)
+        return all(qp.completed for qp in self.quest_progressions if qp.completable)
 
     @property
     def failed(self) -> bool:
@@ -917,7 +922,7 @@ def winning_policy(self) -> Optional[List[Action]]:
             return None
 
         # Greedily build a new winning policy by merging all quest trees.
-        trees = [quest._tree for quest in self.quest_progressions if not quest.done]
+        trees = [quest._tree for quest in self.quest_progressions if quest.completable and not quest.done]
         if None in trees:
             # Some quests don't have triggering policy.
             return None

textworld/generator/tests/test_game.py

@@ -620,16 +620,13 @@ def setUpClass(cls):
         cls.questB = Quest(win_events=[cls.eventB], fail_events=[cls.losing_eventB])
         cls.questC = Quest(win_events=[], fail_events=[cls.losing_eventA, cls.losing_eventB])
 
-        commands = ["open wooden door", "go west", "take lettuce", "go east", "insert lettuce into chest"]
-        cls.questC = M.new_quest_using_commands(commands)
-
         commands = ["open wooden door", "go west", "take carrot", "eat carrot"]
         cls.eating_carrot = M.new_event_using_commands(commands)
         commands = ["open wooden door", "go west", "take lettuce", "eat lettuce"]
         cls.eating_lettuce = M.new_event_using_commands(commands)
         commands = ["open wooden door", "go west", "take lettuce", "go east", "insert lettuce into chest"]
 
-        M.quests = [cls.questA, cls.questB]
+        M.quests = [cls.questA, cls.questB, cls.questC]
         cls.game = M.build()
 
     def test_completed(self):