Fix warning in quickstart.py

.circleci/config.yml

@@ -365,6 +365,10 @@ jobs:
             TESTFILES=$(circleci tests glob "tests/**/test*.py" | circleci tests split --split-by=timings)
             echo "This shard testing: ${TESTFILES}"
             pytest -n auto --junitxml=/tmp/test-reports/junit.xml -vv $TESTFILES
+          environment:
+            # This is needed in newer versions of pygame. See
+            # https://github.com/pygame/pygame/issues/3835#issuecomment-1703717368
+            SDL_VIDEODRIVER: dummy
 
       - save-pytest-cache
       - store-test-output-unix

examples/quickstart.py

@@ -71,9 +71,16 @@ def sample_expert_transitions():
     rng=rng,
 )
 
+evaluation_env = make_vec_env(
+    "seals:seals/CartPole-v0",
+    rng=rng,
+    env_make_kwargs={"render_mode": "human"},  # for rendering
+)
+
+print("Evaluating the untrained policy.")
 reward, _ = evaluate_policy(
     bc_trainer.policy,  # type: ignore[arg-type]
-    env,
+    evaluation_env,
     n_eval_episodes=3,
     render=True,  # comment out to speed up
 )
@@ -82,9 +89,10 @@ def sample_expert_transitions():
 print("Training a policy using Behavior Cloning")
 bc_trainer.train(n_epochs=1)
 
+print("Evaluating the trained policy.")
 reward, _ = evaluate_policy(
     bc_trainer.policy,  # type: ignore[arg-type]
-    env,
+    evaluation_env,
     n_eval_episodes=3,
     render=True,  # comment out to speed up
 )