Make sure batch env are sent list of commands when calling step funct…

…ion.

textworld/envs/batch/batch_env.py

@@ -156,8 +156,10 @@ def step(self, actions: List[str]) -> Tuple[List[str], int, bool, Dict[str, List
             done: Whether the game is over or not.
             infos: Information requested when creating the environments.
         """
-        results = []
+        assert isinstance(actions, (list, tuple)), "Expected a list of actions."
+        assert len(actions) == len(self.envs), "Expected one action per environment."
 
+        results = []
         for i, (env, action) in enumerate(zip(self.envs, actions)):
             if self.last[i] is not None and self.last[i][2]:  # Game has ended on the last step.
                 obs, reward, done, infos = self.last[i]  # Copy last state over.
@@ -252,6 +254,9 @@ def step(self, actions):
             done: Whether the game is over or not.
             infos: Information requested when creating the environments.
         """
+        assert isinstance(actions, (list, tuple)), "Expected a list of actions."
+        assert len(actions) == len(self.envs), "Expected one action per environment."
+
         results = []
         for i, (env, action) in enumerate(zip(self.envs, actions)):
             if self.last[i] is not None and self.last[i][2]:  # Game has ended on the last step.

textworld/gym/envs/textworld_batch.py

@@ -144,6 +144,8 @@ def step(self, commands) -> Tuple[List[str], List[float], List[bool], Dict[str,
             * dones: whether each game in the batch is finished or not;
             * infos: additional information as requested for each game in the batch.
         """
+        assert isinstance(commands, (list, tuple)), "Expected a list of commands."
+
         self.last_commands = commands
         self.obs, scores, dones, infos = self.batch_env.step(self.last_commands)
         return self.obs, scores, dones, infos

textworld/gym/tests/test_textworld_gym.py

@@ -138,6 +138,14 @@ def test_batch_sync(self):
         for values in infos.values():
             assert len(values) == batch_size
 
+        # Sending single command should raise assertion.
+        with pytest.raises(AssertionError):
+            obs, scores, dones, infos = env.step("wait")
+
+        # Sending not engough commands should raise assertion.
+        with pytest.raises(AssertionError):
+            obs, scores, dones, infos = env.step(["wait"] * (batch_size - 1))
+
         for cmds in zip(*infos.get("extra.walkthrough")):
             obs, scores, dones, infos = env.step(cmds)
 
@@ -165,6 +173,14 @@ def test_batch_async(self):
         for values in infos.values():
             assert len(values) == batch_size
 
+        # Sending single command should raise assertion.
+        with pytest.raises(AssertionError):
+            obs, scores, dones, infos = env.step("wait")
+
+        # Sending not engough commands should raise assertion.
+        with pytest.raises(AssertionError):
+            obs, scores, dones, infos = env.step(["wait"] * (batch_size - 1))
+
         for cmds in zip(*infos.get("extra.walkthrough")):
             obs, scores, dones, infos = env.step(cmds)