Fix typo in IS-MCTS test and add default support for ResampleFromInfo…

…state for perfect information game (defaults to State::Clone()).

PiperOrigin-RevId: 657678805
Change-Id: Ib2560b2cb0a92636a82c7e8efbf84d6d3b6c6b85

open_spiel/python/algorithms/ismcts_agent_test.py

@@ -14,16 +14,21 @@
 """Test the IS-MCTS Agent."""
 
 from absl.testing import absltest
+from absl.testing import parameterized
 from open_spiel.python import rl_environment
 from open_spiel.python.algorithms import ismcts
 from open_spiel.python.algorithms import mcts
 from open_spiel.python.algorithms import mcts_agent
 
 
-class MCTSAgentTest(absltest.TestCase):
+class MCTSAgentTest(parameterized.TestCase):
 
-  def test_tic_tac_toe_episode(self):
-    env = rl_environment.Environment("kuhn_poker", include_full_state=True)
+  @parameterized.named_parameters(
+      dict(testcase_name="tic_tac_toe", game_string="kuhn_poker"),
+      dict(testcase_name="leduc_poker", game_string="leduc_poker"),
+  )
+  def test_self_play_episode(self, game_string: str):
+    env = rl_environment.Environment(game_string, include_full_state=True)
     num_players = env.num_players
     num_actions = env.action_spec()["num_actions"]
 

open_spiel/spiel.cc

@@ -127,6 +127,16 @@ StateType State::GetType() const {
   }
 }
 
+std::unique_ptr<State> State::ResampleFromInfostate(
+    int player_id,
+    std::function<double()> rng) const {
+  if (GetGame()->GetType().information ==
+      GameType::Information::kPerfectInformation) {
+    return Clone();
+  }
+  SpielFatalError("ResampleFromInfostate() not implemented.");
+}
+
 bool GameType::ContainsRequiredParameters() const {
   for (const auto& key_val : parameter_specification) {
     if (key_val.second.is_mandatory()) {

open_spiel/spiel.h

@@ -654,10 +654,11 @@ class State {
   // be interpreted as a cumulative distribution function, and will be used to
   // sample from the legal chance actions. A good choice would be
   // absl/std::uniform_real_distribution<double>(0., 1.).
+  //
+  // Default implementation checks if the game is a perfect information game.
+  // If so, it returns a clone, otherwise an error is thrown.
   virtual std::unique_ptr<State> ResampleFromInfostate(
-      int player_id, std::function<double()> rng) const {
-    SpielFatalError("ResampleFromInfostate() not implemented.");
-  }
+      int player_id, std::function<double()> rng) const;
 
   // Returns a vector of states & probabilities that are consistent with the
   // infostate from the view of the current player. By default, this is not