test(llmrails): characterize public compatibility behavior

Pin public LLMRails state, sync wrappers, update_llm binding behavior, and pickle behavior before extracting internals.

Author: Pouyanpi

tests/rails/llm/test_llmrails_public_contract.py

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+# SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import pytest
+
+from nemoguardrails import LLMRails, RailsConfig
+from tests.utils import FakeLLMModel
+
+
+def _config() -> RailsConfig:
+    return RailsConfig.from_content(config={"models": []})
+
+
+def test_constructor_keeps_public_state_visible():
+    config = _config()
+    llm = FakeLLMModel(responses=[])
+
+    rails = LLMRails(config=config, llm=llm)
+
+    assert rails.config is config
+    assert rails.llm is llm
+    assert rails.runtime is not None
+    assert rails.llm_generation_actions is not None
+    assert rails.events_history_cache == {}
+    assert rails.explain_info is None
+
+
+def test_update_llm_keeps_runtime_generation_actions_and_public_attr_in_sync():
+    rails = LLMRails(config=_config(), llm=FakeLLMModel(responses=[]))
+    new_llm = FakeLLMModel(responses=["updated"])
+
+    rails.update_llm(new_llm)
+
+    assert rails.llm is new_llm
+    assert rails.llm_generation_actions.llm is new_llm
+    assert rails.runtime.registered_action_params["llm"] is new_llm
+
+
+@pytest.mark.asyncio
+async def test_sync_wrappers_raise_when_called_from_async_loop():
+    rails = LLMRails(config=_config(), llm=FakeLLMModel(responses=[]))
+
+    with pytest.raises(RuntimeError, match="sync `generate` inside async code"):
+        rails.generate(prompt="hi")
+
+    with pytest.raises(RuntimeError, match="sync `generate_events` inside async code"):
+        rails.generate_events([])
+
+    with pytest.raises(RuntimeError, match="sync `generate_events` inside async code"):
+        rails.process_events([])
+
+    with pytest.raises(RuntimeError, match="sync `check` inside async code"):
+        rails.check([{"role": "user", "content": "hi"}])
+
+
+def test_getstate_serializes_config_only():
+    rails = LLMRails(config=_config(), llm=FakeLLMModel(responses=[]))
+    rails.events_history_cache["cached"] = [{"type": "CachedEvent"}]
+    rails.register_action_param("custom_param", object())
+
+    state = rails.__getstate__()
+
+    assert state == {"config": rails.config}