refactor(env): introduce explicit gym ID handling in EnvConfig/factory (#2234)

* refactor(env): introduce explicit gym ID handling in EnvConfig/factory

This commit introduces properties for the gym package/ID associated
with and environment config. They default to the current defaults
(`gym_{package_name}/{task_id}`) to avoid breaking changes, but allow
for easier use of external gym environments.

Subclasses of `EnvConfig` can override the default properties to allow
the factory to import (i.e. register) the gym env from a specific module,
and also instantiate the env from any ID string.

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* more changes

* quality

* fix test

---------

Co-authored-by: Ben Sprenger <ben.sprenger@rogers.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Adil Zouitine <adilzouitinegm@gmail.com>

tests/envs/test_envs.py

@@ -14,13 +14,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import importlib
+from dataclasses import dataclass, field
 
 import gymnasium as gym
 import pytest
 import torch
+from gymnasium.envs.registration import register, registry as gym_registry
 from gymnasium.utils.env_checker import check_env
 
 import lerobot
+from lerobot.configs.types import PolicyFeature
+from lerobot.envs.configs import EnvConfig
 from lerobot.envs.factory import make_env, make_env_config
 from lerobot.envs.utils import preprocess_observation
 from tests.utils import require_env
@@ -64,3 +68,43 @@ def test_factory(env_name):
         assert img.min() >= 0.0
 
     env.close()
+
+
+def test_factory_custom_gym_id():
+    gym_id = "dummy_gym_pkg/DummyTask-v0"
+    if gym_id in gym_registry:
+        pytest.skip(f"Environment ID {gym_id} is already registered")
+
+    @EnvConfig.register_subclass("dummy")
+    @dataclass
+    class DummyEnv(EnvConfig):
+        task: str = "DummyTask-v0"
+        fps: int = 10
+        features: dict[str, PolicyFeature] = field(default_factory=dict)
+
+        @property
+        def package_name(self) -> str:
+            return "dummy_gym_pkg"
+
+        @property
+        def gym_id(self) -> str:
+            return gym_id
+
+        @property
+        def gym_kwargs(self) -> dict:
+            return {}
+
+    try:
+        register(id=gym_id, entry_point="gymnasium.envs.classic_control:CartPoleEnv")
+
+        cfg = DummyEnv()
+        envs_dict = make_env(cfg, n_envs=1)
+        dummy_envs = envs_dict["dummy"]
+        assert len(dummy_envs) == 1
+        env = next(iter(dummy_envs.values()))
+        assert env is not None and isinstance(env, gym.vector.VectorEnv)
+        env.close()
+
+    finally:
+        if gym_id in gym_registry:
+            del gym_registry[gym_id]