810def4fc5
New `langchain_tests.utils.stream_lifecycle.assert_valid_event_stream` helper enforces the protocol contract on any event stream: - single message-start / message-finish envelope - blocks do not interleave (each block finishes before the next starts) - sequential uint wire indices from 0 - accumulated deltas match the finish payload for deltaable types Applied at three levels: - core/test_compat_bridge: provider-style emission patterns exercised directly through chunks_to_events / message_to_events (openai chat completions int indices, openai responses/v1 string identifiers, anthropic-style per-chunk int indices, inline image, invalid tool call, empty stream) - openai partner: validator applied to stream_v2 against the existing responses-api mock and to a new chat-completions stream_v2 test - anthropic partner: new mock stream of RawMessageStartEvent + RawContentBlock* events threaded through _stream via `_create` patch; covers thinking + text + tool_use lifecycle with tool-use stop_reason Enabling thinking on the anthropic test flips coerce_content_to_string off so every block carries a proper integer index — the structured path the bridge actually exercises. Default-mode (no tools / thinking / docs) coerces text to a plain string and strips per-chunk indices; the bridge handles that branch by collapsing to positional-0 and it is a known separate code path, intentionally not covered here.
🦜️🔗 langchain-tests
Looking for the JS/TS version? Check out LangChain.js.
Quick Install
pip install langchain-tests
🤔 What is this?
This is a testing library for LangChain integrations. It contains the base classes for a standard set of tests.
📖 Documentation
For full documentation, see the API reference.
📕 Releases & Versioning
See our Releases and Versioning policies.
We encourage pinning your version to a specific version in order to avoid breaking your CI when we publish new tests. We recommend upgrading to the latest version periodically to make sure you have the latest tests.
Not pinning your version will ensure you always have the latest tests, but it may also break your CI if we introduce tests that your integration doesn't pass.
💁 Contributing
As an open-source project in a rapidly developing field, we are extremely open to contributions, whether it be in the form of a new feature, improved infrastructure, or better documentation.
For detailed information on how to contribute, see the Contributing Guide.
Usage
To add standard tests to an integration package (e.g., for a chat model), you need to create
- A unit test class that inherits from
ChatModelUnitTests - An integration test class that inherits from
ChatModelIntegrationTests
tests/unit_tests/test_standard.py:
"""Standard LangChain interface tests"""
from typing import Type
import pytest
from langchain_core.language_models import BaseChatModel
from langchain_tests.unit_tests import ChatModelUnitTests
from langchain_parrot_chain import ChatParrotChain
class TestParrotChainStandard(ChatModelUnitTests):
@pytest.fixture
def chat_model_class(self) -> Type[BaseChatModel]:
return ChatParrotChain
tests/integration_tests/test_standard.py:
"""Standard LangChain interface tests"""
from typing import Type
import pytest
from langchain_core.language_models import BaseChatModel
from langchain_tests.integration_tests import ChatModelIntegrationTests
from langchain_parrot_chain import ChatParrotChain
class TestParrotChainStandard(ChatModelIntegrationTests):
@pytest.fixture
def chat_model_class(self) -> Type[BaseChatModel]:
return ChatParrotChain
Reference
The following fixtures are configurable in the test classes. Anything not marked as required is optional.
chat_model_class(required): The class of the chat model to be testedchat_model_params: The keyword arguments to pass to the chat model constructorchat_model_has_tool_calling: Whether the chat model can call tools. By default, this is set tohasattr(chat_model_class, 'bind_tools)chat_model_has_structured_output: Whether the chat model can structured output. By default, this is set tohasattr(chat_model_class, 'with_structured_output')