[rllib] Fix VectorEnv's check for the info object's type (#10982)

rllib/env/vector_env.py

@@ -145,7 +145,7 @@ class _VectorizedGymEnv(VectorEnv):
                 raise ValueError(
                     "Reward should be finite scalar, got {} ({}). "
                     "Actions={}.".format(r, type(r), actions[i]))
-            if type(info) is not dict:
+            if not isinstance(info, dict):
                 raise ValueError("Info should be a dict, got {} ({})".format(
                     info, type(info)))
             obs_batch.append(obs)

rllib/tests/test_vector_env.py

@@ -0,0 +1,32 @@
+import gym
+import unittest
+
+from ray.rllib.env.vector_env import VectorEnv
+
+
+class Info(dict):
+    pass
+
+
+class MockEnvDictSubclass(gym.Env):
+    def __init__(self):
+        self.observation_space = gym.spaces.Discrete(1)
+        self.action_space = gym.spaces.Discrete(2)
+
+    def reset(self):
+        return 0
+
+    def step(self, action):
+        return 0, 1, True, Info()
+
+
+class TestExternalEnv(unittest.TestCase):
+    def test_vector_step(self):
+        env = VectorEnv.wrap(lambda _: MockEnvDictSubclass(), num_envs=3)
+        env.vector_step([0] * 3)
+
+
+if __name__ == "__main__":
+    import pytest
+    import sys
+    sys.exit(pytest.main(["-v", __file__]))