mixed behav profile: payoff, infoset_value, and action_value all thro…

…w value errors when called with the chance player

ChangeLog

@@ -6,6 +6,8 @@
 - Empty or all-whitespace strings cannot be used to access members of games in pygambit.
 - Remaining compatibility code for wxWidgets 2.x removed from graphical interface.
 - Migrated to pytest for testing of pygambit.
+- ValueErrors raised for mixed behavior profiles when payoff, action_value, or infoset_value are
+  called with the chance player.
 
 
 ## [16.1.0a3] - 2023-09-29

src/pygambit/behav.pxi

@@ -284,8 +284,13 @@ class MixedBehaviorProfile:
             If `player` is a `Player` from a different game.
         KeyError
             If `player` is a string and no player in the game has that label.
+        ValueError
+            If `player` resolves to the chance player
         """
-        return self._payoff(self.game._resolve_player(player, 'payoff'))
+        resolved_player = self.game._resolve_player(player, 'payoff')
+        if resolved_player.is_chance:
+            raise ValueError("payoff() is not defined for the chance player")
+        return self._payoff(resolved_player)
 
     def infoset_value(self, infoset: typing.Union[Infoset, str]):
         """Returns the expected payoff to the player conditional on reaching an information set,
@@ -303,8 +308,13 @@ class MixedBehaviorProfile:
             If `infoset` is an `Infoset` from a different game.
         KeyError
             If `infoset` is a string and no information set in the game has that label.
+        ValueError
+            If `infoset` resolves to an infoset that belongs to the chance player
         """
-        return self._infoset_value(self.game._resolve_infoset(infoset, 'infoset_value'))
+        resolved_infoset = self.game._resolve_infoset(infoset, 'infoset_value')
+        if resolved_infoset.player.is_chance:
+            raise ValueError("infoset_value() is not defined for the chance player")
+        return self._infoset_value(resolved_infoset)
 
     def action_value(self, action: typing.Union[Action, str]):
         """Returns the expected payoff to the player of playing an action conditional on reaching its
@@ -322,8 +332,13 @@ class MixedBehaviorProfile:
             If `action` is an `Action` from a different game.
         KeyError
             If `action` is a string and no action in the game has that label.
+        ValueError
+            If `action` resolves to an action that belongs to the chance player
         """
-        return self._action_value(self.game._resolve_action(action, 'action_value'))
+        resolved_action = self.game._resolve_action(action, 'action_value')
+        if resolved_action.infoset.player.is_chance:
+            raise ValueError("action_value() is not defined for the chance player")
+        return self._action_value(resolved_action)
 
     def infoset_prob(self, infoset: typing.Union[Infoset, str]):
         """Returns the probability with which an information set is reached.

src/pygambit/tests/test_behav.py

@@ -11,6 +11,12 @@ def setUp(self):
         self.profile_double = self.game.mixed_behavior_profile()
         self.profile_rational = self.game.mixed_behavior_profile(True)
 
+        self.game_with_chance = gbt.Game.read_game(
+            "test_games/complicated_extensive_game.efg"
+        )
+        self.profile_double_with_chance = self.game_with_chance.mixed_behavior_profile()
+        self.profile_rational_with_chance = self.game_with_chance.mixed_behavior_profile(True)
+
     def tearDown(self):
         del self.game
         del self.profile_double
@@ -724,3 +730,29 @@ def test_infoset_belief(self):
             self.profile_rational.belief(self.game.infosets[0].members[0]) ==
             gbt.Rational(1, 1)
         )
+
+    def test_payoff_with_chance_player(self):
+        """Test to ensure that payoff called with the chance player raises a ValueError"""
+        chance_player = self.game_with_chance.players.chance
+        self.assertRaises(ValueError, self.profile_double_with_chance.payoff, chance_player)
+        self.assertRaises(ValueError, self.profile_rational_with_chance.payoff, chance_player)
+
+    def test_infoset_value_with_chance_player_infoset(self):
+        """Test to ensure that infoset_value called with an infoset of the chance player
+        raises a ValueError
+        """
+        chance_infoset = self.game_with_chance.players.chance.infosets[0]
+        self.assertRaises(ValueError, self.profile_double_with_chance.infoset_value,
+                          chance_infoset)
+        self.assertRaises(ValueError, self.profile_rational_with_chance.infoset_value,
+                          chance_infoset)
+
+    def test_action_value_with_chance_player_action(self):
+        """Test to ensure that action_value called with an action of the chance player
+        raises a ValueError
+        """
+        chance_action = self.game_with_chance.players.chance.infosets[0].actions[0]
+        self.assertRaises(ValueError, self.profile_double_with_chance.action_value,
+                          chance_action)
+        self.assertRaises(ValueError, self.profile_rational_with_chance.action_value,
+                          chance_action)