stable-baselines3/tests/test_save_load.py

import base64
import io
import json
import os
import pathlib
import warnings
import zipfile
from collections import OrderedDict
from copy import deepcopy

import gymnasium as gym
import numpy as np
import pytest
import torch as th

from stable_baselines3 import A2C, DDPG, DQN, PPO, SAC, TD3
from stable_baselines3.common.base_class import BaseAlgorithm
from stable_baselines3.common.envs import FakeImageEnv, IdentityEnv, IdentityEnvBox
from stable_baselines3.common.save_util import load_from_pkl, open_path, save_to_pkl
from stable_baselines3.common.utils import get_device
from stable_baselines3.common.vec_env import DummyVecEnv

MODEL_LIST = [PPO, A2C, TD3, SAC, DQN, DDPG]


def select_env(model_class: BaseAlgorithm) -> gym.Env:
    """
    Selects an environment with the correct action space as DQN only supports discrete action space
    """
    if model_class == DQN:
        return IdentityEnv(10)
    else:
        return IdentityEnvBox(-10, 10)


@pytest.mark.parametrize("model_class", MODEL_LIST)
def test_save_load(tmp_path, model_class):
    """
    Test if 'save' and 'load' saves and loads model correctly
    and if 'get_parameters' and 'set_parameters' and work correctly.

    ''warning does not test function of optimizer parameter load

    :param model_class: (BaseAlgorithm) A RL model
    """

    env = DummyVecEnv([lambda: select_env(model_class)])

    # create model
    model = model_class("MlpPolicy", env, policy_kwargs=dict(net_arch=[16]), verbose=1)
    model.learn(total_timesteps=500)

    env.reset()
    observations = np.concatenate([env.step([env.action_space.sample()])[0] for _ in range(10)], axis=0)

    # Get parameters of different objects
    # deepcopy to avoid referencing to tensors we are about to modify
    original_params = deepcopy(model.get_parameters())

    # Test different error cases of set_parameters.
    # Test that invalid object names throw errors
    invalid_object_params = deepcopy(original_params)
    invalid_object_params["I_should_not_be_a_valid_object"] = "and_I_am_an_invalid_tensor"
    with pytest.raises(ValueError):
        model.set_parameters(invalid_object_params, exact_match=True)
    with pytest.raises(ValueError):
        model.set_parameters(invalid_object_params, exact_match=False)

    # Test that exact_match catches when something was missed.
    missing_object_params = {k: v for k, v in list(original_params.items())[:-1]}
    with pytest.raises(ValueError):
        model.set_parameters(missing_object_params, exact_match=True)

    # Test that exact_match catches when something inside state-dict
    # is missing but we have exact_match.
    missing_state_dict_tensor_params = {}
    for object_name in original_params:
        object_params = {}
        missing_state_dict_tensor_params[object_name] = object_params
        # Skip last item in state-dict
        for k, v in list(original_params[object_name].items())[:-1]:
            object_params[k] = v
    with pytest.raises(RuntimeError):
        # PyTorch load_state_dict throws RuntimeError if strict but
        # invalid state-dict.
        model.set_parameters(missing_state_dict_tensor_params, exact_match=True)

    # Test that parameters do indeed change.
    random_params = {}
    for object_name, params in original_params.items():
        # Do not randomize optimizer parameters (custom layout)
        if "optim" in object_name:
            random_params[object_name] = params
        else:
            # Again, skip the last item in state-dict
            random_params[object_name] = OrderedDict(
                (param_name, th.rand_like(param)) for param_name, param in list(params.items())[:-1]
            )

    # Update model parameters with the new random values
    model.set_parameters(random_params, exact_match=False)

    new_params = model.get_parameters()
    # Check that all params except the final item in each state-dict are different.
    for object_name in original_params:
        # Skip optimizers (no valid comparison with just th.allclose)
        if "optim" in object_name:
            continue
        # state-dicts use ordered dictionaries, so key order
        # is guaranteed.
        last_key = list(original_params[object_name].keys())[-1]
        for k in original_params[object_name]:
            if k == last_key:
                # Should be same as before
                assert th.allclose(
                    original_params[object_name][k], new_params[object_name][k]
                ), "Parameter changed despite not included in the loaded parameters."
            else:
                # Should be different
                assert not th.allclose(
                    original_params[object_name][k], new_params[object_name][k]
                ), "Parameters did not change as expected."

    params = new_params

    # get selected actions
    selected_actions, _ = model.predict(observations, deterministic=True)

    # Check
    model.save(tmp_path / "test_save.zip")
    del model

    # Check if the model loads as expected for every possible choice of device:
    for device in ["auto", "cpu", "cuda"]:
        model = model_class.load(str(tmp_path / "test_save.zip"), env=env, device=device)

        # check if the model was loaded to the correct device
        assert model.device.type == get_device(device).type
        assert model.policy.device.type == get_device(device).type

        # check if params are still the same after load
        new_params = model.get_parameters()

        # Check that all params are the same as before save load procedure now
        for object_name in new_params:
            # Skip optimizers (no valid comparison with just th.allclose)
            if "optim" in object_name:
                continue
            for key in params[object_name]:
                assert new_params[object_name][key].device.type == get_device(device).type
                assert th.allclose(
                    params[object_name][key].to("cpu"), new_params[object_name][key].to("cpu")
                ), "Model parameters not the same after save and load."

        # check if model still selects the same actions
        new_selected_actions, _ = model.predict(observations, deterministic=True)
        assert np.allclose(selected_actions, new_selected_actions, 1e-4)

        # check if learn still works
        model.learn(total_timesteps=500)

        del model

    # clear file from os
    os.remove(tmp_path / "test_save.zip")


@pytest.mark.parametrize("model_class", MODEL_LIST)
def test_set_env(tmp_path, model_class):
    """
    Test if set_env function does work correct

    :param model_class: (BaseAlgorithm) A RL model
    """

    # use discrete for DQN
    env = DummyVecEnv([lambda: select_env(model_class)])
    env2 = DummyVecEnv([lambda: select_env(model_class)])
    env3 = select_env(model_class)
    env4 = DummyVecEnv([lambda: select_env(model_class) for _ in range(2)])

    kwargs = {}
    if model_class in {DQN, DDPG, SAC, TD3}:
        kwargs = dict(learning_starts=50, train_freq=4)
    elif model_class in {A2C, PPO}:
        kwargs = dict(n_steps=64)

    # create model
    model = model_class("MlpPolicy", env, policy_kwargs=dict(net_arch=[16]), **kwargs)
    # learn
    model.learn(total_timesteps=64)

    # change env
    model.set_env(env2, force_reset=True)
    # Check that last obs was discarded
    assert model._last_obs is None
    # learn again
    model.learn(total_timesteps=64, reset_num_timesteps=True)
    assert model.num_timesteps == 64

    # change env test wrapping
    model.set_env(env3)
    # learn again
    model.learn(total_timesteps=64)

    # num_env must be the same
    with pytest.raises(AssertionError):
        model.set_env(env4)

    # Keep the same env, disable reset
    model.set_env(model.get_env(), force_reset=False)
    assert model._last_obs is not None
    # learn again
    model.learn(total_timesteps=64, reset_num_timesteps=False)
    assert model.num_timesteps == 2 * 64

    current_env = model.get_env()
    model.save(tmp_path / "test_save.zip")
    del model
    # Check that we can keep the number of timesteps after loading
    # Here the env kept its state so we don't have to reset
    model = model_class.load(tmp_path / "test_save.zip", env=current_env, force_reset=False)
    assert model._last_obs is not None
    model.learn(total_timesteps=64, reset_num_timesteps=False)
    assert model.num_timesteps == 3 * 64

    del model
    # We are changing the env, the env must reset but we should keep the number of timesteps
    model = model_class.load(tmp_path / "test_save.zip", env=env3, force_reset=True)
    assert model._last_obs is None
    model.learn(total_timesteps=64, reset_num_timesteps=False)
    assert model.num_timesteps == 3 * 64

    del model
    # Load the model with a different number of environments
    model = model_class.load(tmp_path / "test_save.zip", env=env4)
    model.learn(total_timesteps=64)

    # Clear saved file
    os.remove(tmp_path / "test_save.zip")


@pytest.mark.parametrize("model_class", MODEL_LIST)
def test_exclude_include_saved_params(tmp_path, model_class):
    """
    Test if exclude and include parameters of save() work

    :param model_class: (BaseAlgorithm) A RL model
    """
    env = DummyVecEnv([lambda: select_env(model_class)])

    # create model, set verbose as 2, which is not standard
    model = model_class("MlpPolicy", env, policy_kwargs=dict(net_arch=[16]), verbose=2)

    # Check if exclude works
    model.save(tmp_path / "test_save", exclude=["verbose"])
    del model
    model = model_class.load(str(tmp_path / "test_save.zip"))
    # check if verbose was not saved
    assert model.verbose != 2

    # set verbose as something different then standard settings
    model.verbose = 2
    # Check if include works
    model.save(tmp_path / "test_save", exclude=["verbose"], include=["verbose"])
    del model
    # Load with custom objects
    custom_objects = dict(learning_rate=2e-5, dummy=1.0)
    model = model_class.load(
        str(tmp_path / "test_save.zip"),
        custom_objects=custom_objects,
        print_system_info=True,
    )
    assert model.verbose == 2
    # Check that the custom object was taken into account
    assert model.learning_rate == custom_objects["learning_rate"]
    # Check that only parameters that are here already are replaced
    assert not hasattr(model, "dummy")

    # clear file from os
    os.remove(tmp_path / "test_save.zip")


def test_save_load_pytorch_var(tmp_path):
    model = SAC("MlpPolicy", "Pendulum-v1", seed=3, policy_kwargs=dict(net_arch=[64], n_critics=1))
    model.learn(200)
    save_path = str(tmp_path / "sac_pendulum")
    model.save(save_path)
    env = model.get_env()
    log_ent_coef_before = model.log_ent_coef

    del model

    model = SAC.load(save_path, env=env)
    assert th.allclose(log_ent_coef_before, model.log_ent_coef)
    model.learn(200)
    log_ent_coef_after = model.log_ent_coef
    # Check that the entropy coefficient is still optimized
    assert not th.allclose(log_ent_coef_before, log_ent_coef_after)

    # With a fixed entropy coef
    model = SAC("MlpPolicy", "Pendulum-v1", seed=3, ent_coef=0.01, policy_kwargs=dict(net_arch=[64], n_critics=1))
    model.learn(200)
    save_path = str(tmp_path / "sac_pendulum")
    model.save(save_path)
    env = model.get_env()
    assert model.log_ent_coef is None
    ent_coef_before = model.ent_coef_tensor

    del model

    model = SAC.load(save_path, env=env)
    assert th.allclose(ent_coef_before, model.ent_coef_tensor)
    model.learn(200)
    ent_coef_after = model.ent_coef_tensor
    assert model.log_ent_coef is None
    # Check that the entropy coefficient is still the same
    assert th.allclose(ent_coef_before, ent_coef_after)


@pytest.mark.parametrize("model_class", [A2C, TD3])
def test_save_load_env_cnn(tmp_path, model_class):
    """
    Test loading with an env that requires a ``CnnPolicy``.
    This is to test wrapping and observation space check.
    We test one on-policy and one off-policy
    algorithm as the rest share the loading part.
    """
    env = FakeImageEnv(screen_height=40, screen_width=40, n_channels=2, discrete=False)
    kwargs = dict(policy_kwargs=dict(net_arch=[32]))
    if model_class == TD3:
        kwargs.update(dict(buffer_size=100, learning_starts=50, train_freq=4))

    model = model_class("CnnPolicy", env, **kwargs).learn(100)
    model.save(tmp_path / "test_save")
    # Test loading with env and continuing training
    model = model_class.load(str(tmp_path / "test_save.zip"), env=env, **kwargs).learn(100)
    # clear file from os
    os.remove(tmp_path / "test_save.zip")

    # Check we can load models saved with SB3 < 1.7.0
    if model_class == A2C:
        del model.policy.pi_features_extractor
        model.save(tmp_path / "test_save")
        with pytest.warns(UserWarning):
            model_class.load(str(tmp_path / "test_save.zip"), env=env, **kwargs).learn(100)
        os.remove(tmp_path / "test_save.zip")


@pytest.mark.parametrize("model_class", [SAC, TD3, DQN])
def test_save_load_replay_buffer(tmp_path, model_class):
    path = pathlib.Path(tmp_path / "logs/replay_buffer.pkl")
    path.parent.mkdir(exist_ok=True, parents=True)  # to not raise a warning
    model = model_class(
        "MlpPolicy", select_env(model_class), buffer_size=1000, policy_kwargs=dict(net_arch=[64]), learning_starts=200
    )
    model.learn(300)
    old_replay_buffer = deepcopy(model.replay_buffer)
    model.save_replay_buffer(path)
    model.replay_buffer = None
    model.load_replay_buffer(path)

    assert np.allclose(old_replay_buffer.observations, model.replay_buffer.observations)
    assert np.allclose(old_replay_buffer.actions, model.replay_buffer.actions)
    assert np.allclose(old_replay_buffer.rewards, model.replay_buffer.rewards)
    assert np.allclose(old_replay_buffer.dones, model.replay_buffer.dones)
    assert np.allclose(old_replay_buffer.timeouts, model.replay_buffer.timeouts)
    infos = [[{"TimeLimit.truncated": truncated}] for truncated in old_replay_buffer.timeouts]

    # test extending replay buffer
    model.replay_buffer.extend(
        old_replay_buffer.observations,
        old_replay_buffer.observations,
        old_replay_buffer.actions,
        old_replay_buffer.rewards,
        old_replay_buffer.dones,
        infos,
    )


@pytest.mark.parametrize("model_class", [DQN, SAC, TD3])
@pytest.mark.parametrize("optimize_memory_usage", [False, True])
def test_warn_buffer(recwarn, model_class, optimize_memory_usage):
    """
    When using memory efficient replay buffer,
    a warning must be emitted when calling `.learn()`
    multiple times.
    See https://github.com/DLR-RM/stable-baselines3/issues/46
    """
    # remove gym warnings
    warnings.filterwarnings(action="ignore", category=DeprecationWarning)
    warnings.filterwarnings(action="ignore", category=UserWarning, module="gym")

    model = model_class(
        "MlpPolicy",
        select_env(model_class),
        buffer_size=100,
        optimize_memory_usage=optimize_memory_usage,
        # we cannot use optimize_memory_usage and handle_timeout_termination
        # at the same time
        replay_buffer_kwargs={"handle_timeout_termination": not optimize_memory_usage},
        policy_kwargs=dict(net_arch=[64]),
        learning_starts=10,
    )

    model.learn(150)

    model.learn(150, reset_num_timesteps=False)

    # Check that there is no warning
    assert len(recwarn) == 0

    model.learn(150)

    if optimize_memory_usage:
        assert len(recwarn) == 1
        warning = recwarn.pop(UserWarning)
        assert "The last trajectory in the replay buffer will be truncated" in str(warning.message)
    else:
        assert len(recwarn) == 0


@pytest.mark.parametrize("model_class", MODEL_LIST)
@pytest.mark.parametrize("policy_str", ["MlpPolicy", "CnnPolicy"])
@pytest.mark.parametrize("use_sde", [False, True])
def test_save_load_policy(tmp_path, model_class, policy_str, use_sde):
    """
    Test saving and loading policy only.

    :param model_class: (BaseAlgorithm) A RL model
    :param policy_str: (str) Name of the policy.
    """
    kwargs = dict(policy_kwargs=dict(net_arch=[16]))

    # gSDE is only applicable for A2C, PPO and SAC
    if use_sde and model_class not in [A2C, PPO, SAC]:
        pytest.skip()

    if policy_str == "MlpPolicy":
        env = select_env(model_class)
    else:
        if model_class in [SAC, TD3, DQN, DDPG]:
            # Avoid memory error when using replay buffer
            # Reduce the size of the features
            kwargs = dict(
                buffer_size=250, learning_starts=100, policy_kwargs=dict(features_extractor_kwargs=dict(features_dim=32))
            )
        env = FakeImageEnv(screen_height=40, screen_width=40, n_channels=2, discrete=model_class == DQN)

    if use_sde:
        kwargs["use_sde"] = True

    env = DummyVecEnv([lambda: env])

    # create model
    model = model_class(policy_str, env, verbose=1, **kwargs)
    model.learn(total_timesteps=300)

    env.reset()
    observations = np.concatenate([env.step([env.action_space.sample()])[0] for _ in range(10)], axis=0)

    policy = model.policy
    policy_class = policy.__class__
    actor, actor_class = None, None
    if model_class in [SAC, TD3]:
        actor = policy.actor
        actor_class = actor.__class__

    # Get dictionary of current parameters
    params = deepcopy(policy.state_dict())

    # Modify all parameters to be random values
    random_params = {param_name: th.rand_like(param) for param_name, param in params.items()}

    # Update model parameters with the new random values
    policy.load_state_dict(random_params)

    new_params = policy.state_dict()
    # Check that all params are different now
    for k in params:
        assert not th.allclose(params[k], new_params[k]), "Parameters did not change as expected."

    params = new_params

    # get selected actions
    selected_actions, _ = policy.predict(observations, deterministic=True)
    # Should also work with the actor only
    if actor is not None:
        selected_actions_actor, _ = actor.predict(observations, deterministic=True)

    # Save and load policy
    policy.save(tmp_path / "policy.pkl")
    # Save and load actor
    if actor is not None:
        actor.save(tmp_path / "actor.pkl")

    del policy, actor

    policy = policy_class.load(tmp_path / "policy.pkl")
    if actor_class is not None:
        actor = actor_class.load(tmp_path / "actor.pkl")

    # check if params are still the same after load
    new_params = policy.state_dict()

    # Check that all params are the same as before save load procedure now
    for key in params:
        assert th.allclose(params[key], new_params[key]), "Policy parameters not the same after save and load."

    # check if model still selects the same actions
    new_selected_actions, _ = policy.predict(observations, deterministic=True)
    assert np.allclose(selected_actions, new_selected_actions, 1e-4)

    if actor_class is not None:
        new_selected_actions_actor, _ = actor.predict(observations, deterministic=True)
        assert np.allclose(selected_actions_actor, new_selected_actions_actor, 1e-4)
        assert np.allclose(selected_actions_actor, new_selected_actions, 1e-4)

    # clear file from os
    os.remove(tmp_path / "policy.pkl")
    if actor_class is not None:
        os.remove(tmp_path / "actor.pkl")


@pytest.mark.parametrize("model_class", [DQN])
@pytest.mark.parametrize("policy_str", ["MlpPolicy", "CnnPolicy"])
def test_save_load_q_net(tmp_path, model_class, policy_str):
    """
    Test saving and loading q-network/quantile net only.

    :param model_class: (BaseAlgorithm) A RL model
    :param policy_str: (str) Name of the policy.
    """
    kwargs = dict(policy_kwargs=dict(net_arch=[16]))
    if policy_str == "MlpPolicy":
        env = select_env(model_class)
    else:
        if model_class in [DQN]:
            # Avoid memory error when using replay buffer
            # Reduce the size of the features
            kwargs = dict(
                buffer_size=250,
                learning_starts=100,
                policy_kwargs=dict(features_extractor_kwargs=dict(features_dim=32)),
            )
        env = FakeImageEnv(screen_height=40, screen_width=40, n_channels=2, discrete=model_class == DQN)

    env = DummyVecEnv([lambda: env])

    # create model
    model = model_class(policy_str, env, verbose=1, **kwargs)
    model.learn(total_timesteps=300)

    env.reset()
    observations = np.concatenate([env.step([env.action_space.sample()])[0] for _ in range(10)], axis=0)

    q_net = model.q_net
    q_net_class = q_net.__class__

    # Get dictionary of current parameters
    params = deepcopy(q_net.state_dict())

    # Modify all parameters to be random values
    random_params = {param_name: th.rand_like(param) for param_name, param in params.items()}

    # Update model parameters with the new random values
    q_net.load_state_dict(random_params)

    new_params = q_net.state_dict()
    # Check that all params are different now
    for k in params:
        assert not th.allclose(params[k], new_params[k]), "Parameters did not change as expected."

    params = new_params

    # get selected actions
    selected_actions, _ = q_net.predict(observations, deterministic=True)

    # Save and load q_net
    q_net.save(tmp_path / "q_net.pkl")

    del q_net

    q_net = q_net_class.load(tmp_path / "q_net.pkl")

    # check if params are still the same after load
    new_params = q_net.state_dict()

    # Check that all params are the same as before save load procedure now
    for key in params:
        assert th.allclose(params[key], new_params[key]), "Policy parameters not the same after save and load."

    # check if model still selects the same actions
    new_selected_actions, _ = q_net.predict(observations, deterministic=True)
    assert np.allclose(selected_actions, new_selected_actions, 1e-4)

    # clear file from os
    os.remove(tmp_path / "q_net.pkl")


@pytest.mark.parametrize("pathtype", [str, pathlib.Path])
def test_open_file_str_pathlib(tmp_path, pathtype):
    # check that suffix isn't added because we used open_path first
    with open_path(pathtype(f"{tmp_path}/t1"), "w") as fp1:
        save_to_pkl(fp1, "foo")
    assert fp1.closed
    with warnings.catch_warnings(record=True) as record:
        assert load_from_pkl(pathtype(f"{tmp_path}/t1")) == "foo"
    assert not record

    # test custom suffix
    with open_path(pathtype(f"{tmp_path}/t1.custom_ext"), "w") as fp1:
        save_to_pkl(fp1, "foo")
    assert fp1.closed
    with warnings.catch_warnings(record=True) as record:
        assert load_from_pkl(pathtype(f"{tmp_path}/t1.custom_ext")) == "foo"
    assert not record

    # test without suffix
    with open_path(pathtype(f"{tmp_path}/t1"), "w", suffix="pkl") as fp1:
        save_to_pkl(fp1, "foo")
    assert fp1.closed
    with warnings.catch_warnings(record=True) as record:
        assert load_from_pkl(pathtype(f"{tmp_path}/t1.pkl")) == "foo"
    assert not record

    # test that a warning is raised when the path doesn't exist
    with open_path(pathtype(f"{tmp_path}/t2.pkl"), "w") as fp1:
        save_to_pkl(fp1, "foo")
    assert fp1.closed
    with warnings.catch_warnings(record=True) as record:
        assert load_from_pkl(open_path(pathtype(f"{tmp_path}/t2"), "r", suffix="pkl")) == "foo"
    assert len(record) == 0

    with warnings.catch_warnings(record=True) as record:
        assert load_from_pkl(open_path(pathtype(f"{tmp_path}/t2"), "r", suffix="pkl", verbose=2)) == "foo"
    assert len(record) == 1

    fp = pathlib.Path(f"{tmp_path}/t2").open("w")
    fp.write("rubbish")
    fp.close()
    # test that a warning is only raised when verbose = 0
    with warnings.catch_warnings(record=True) as record:
        open_path(pathtype(f"{tmp_path}/t2"), "w", suffix="pkl", verbose=0).close()
        open_path(pathtype(f"{tmp_path}/t2"), "w", suffix="pkl", verbose=1).close()
        open_path(pathtype(f"{tmp_path}/t2"), "w", suffix="pkl", verbose=2).close()
    assert len(record) == 1


def test_open_file(tmp_path):
    # path must much the type
    with pytest.raises(TypeError):
        open_path(123, None, None, None)

    p1 = tmp_path / "test1"
    fp = p1.open("wb")

    # provided path must match the mode
    with pytest.raises(ValueError):
        open_path(fp, "r")
    with pytest.raises(ValueError):
        open_path(fp, "randomstuff")

    # test identity
    _ = open_path(fp, "w")
    assert _ is not None
    assert fp is _

    # Can't use a closed path
    with pytest.raises(ValueError):
        fp.close()
        open_path(fp, "w")

    buff = io.BytesIO()
    assert buff.writable()
    assert buff.readable() is ("w" == "w")
    _ = open_path(buff, "w")
    assert _ is buff
    with pytest.raises(ValueError):
        buff.close()
        open_path(buff, "w")


@pytest.mark.expensive
def test_save_load_large_model(tmp_path):
    """
    Test saving and loading a model with a large policy that is greater than 2GB. We
    test only one algorithm since all algorithms share the same code for loading and
    saving the model.
    """
    env = select_env(TD3)
    kwargs = dict(policy_kwargs=dict(net_arch=[8192, 8192, 8192]), device="cpu")
    model = TD3("MlpPolicy", env, **kwargs)

    # test saving
    model.save(tmp_path / "test_save")

    # test loading
    model = TD3.load(str(tmp_path / "test_save.zip"), env=env, **kwargs)

    # clear file from os
    os.remove(tmp_path / "test_save.zip")


def test_load_invalid_object(tmp_path):
    # See GH Issue #1122 for an example
    # of invalid object loading
    path = str(tmp_path / "ppo_pendulum.zip")
    PPO("MlpPolicy", "Pendulum-v1", learning_rate=lambda _: 1.0).save(path)

    with zipfile.ZipFile(path, mode="r") as archive:
        json_data = json.loads(archive.read("data").decode())

    # Intentionally corrupt the data
    serialization = json_data["learning_rate"][":serialized:"]
    base64_object = base64.b64decode(serialization.encode())
    new_bytes = base64_object.replace(b"CodeType", b"CodeTyps")
    base64_encoded = base64.b64encode(new_bytes).decode()
    json_data["learning_rate"][":serialized:"] = base64_encoded
    serialized_data = json.dumps(json_data, indent=4)

    with open(tmp_path / "data", "w") as f:
        f.write(serialized_data)
    # Replace with the corrupted file
    # probably doesn't work on windows
    os.system(f"cd {tmp_path}; zip ppo_pendulum.zip data")
    with pytest.warns(UserWarning, match=r"custom_objects"):
        PPO.load(path)
    # Load with custom object, no warnings
    with warnings.catch_warnings(record=True) as record:
        PPO.load(path, custom_objects=dict(learning_rate=lambda _: 1.0))
    assert len(record) == 0