Fix Mahjong hu check for exposed sets without pair

rlcard/games/mahjong/judger.py

@@ -124,10 +124,8 @@ def judge_hu(self, player):
         hand = [card.get_str() for card in player.hand]
         count_dict = {card: hand.count(card) for card in hand}
         set_count = len(player.pile)
-        if set_count >= 4:
-            return True, set_count
         used = []
-        maximum = 0
+        maximum = set_count
         for each in count_dict:
             if each in used:
                 continue

tests/games/test_mahjong_game.py

@@ -2,8 +2,15 @@
 import numpy as np
 
 from rlcard.games.mahjong.game import MahjongGame as Game
+from rlcard.games.mahjong.card import MahjongCard as Card
+from rlcard.games.mahjong.judger import MahjongJudger as Judger
 from rlcard.games.mahjong.player import MahjongPlayer as Player
 
+
+def _card(card_type, trait):
+    return Card(card_type, trait)
+
+
 class TestMahjongMethods(unittest.TestCase):
 
     def test_get_num_players(self):
@@ -72,5 +79,37 @@ def test_player_get_player_id(self):
         player = Player(0, np.random.RandomState())
         self.assertEqual(0, player.get_player_id())
 
+    def test_judge_hu_requires_pair_with_four_exposed_sets(self):
+        judger = Judger(np.random.RandomState())
+        player = Player(0, np.random.RandomState())
+        player.pile = [
+            [_card('characters', '1')] * 3,
+            [_card('characters', '2')] * 3,
+            [_card('characters', '3')] * 3,
+            [_card('dots', '5')] * 3,
+        ]
+        player.hand = [_card('dots', '6'), _card('bamboo', '4')]
+
+        win, value = judger.judge_hu(player)
+
+        self.assertFalse(win)
+        self.assertEqual(value, 4)
+
+    def test_judge_hu_allows_four_exposed_sets_with_pair(self):
+        judger = Judger(np.random.RandomState())
+        player = Player(0, np.random.RandomState())
+        player.pile = [
+            [_card('characters', '1')] * 3,
+            [_card('characters', '2')] * 3,
+            [_card('characters', '3')] * 3,
+            [_card('dots', '5')] * 3,
+        ]
+        player.hand = [_card('bamboo', '4'), _card('bamboo', '4')]
+
+        win, value = judger.judge_hu(player)
+
+        self.assertTrue(win)
+        self.assertEqual(value, 4)
+
 if __name__ == '__main__':
     unittest.main()