test_create_retriever_tool_get_type_hints() — langchain Function Reference

Source Code

libs/core/tests/unit_tests/test_tools.py lines 2299–2322

def test_create_retriever_tool_get_type_hints() -> None:
    """Verify get_type_hints works on retriever tool's func.

    This test ensures compatibility with Python 3.12+ where get_type_hints()
    raises TypeError on functools.partial objects. Tools like LangGraph's
    ToolNode call get_type_hints(tool.func) to generate schemas.
    """

    class MyRetriever(BaseRetriever):
        @override
        def _get_relevant_documents(
            self, query: str, *, run_manager: CallbackManagerForRetrieverRun
        ) -> list[Document]:
            return [Document(page_content="test")]

    retriever = MyRetriever()
    retriever_tool = tools.create_retriever_tool(
        retriever, "test_tool", "Test tool for type hints"
    )

    # This should not raise TypeError (as it did with functools.partial)
    hints = get_type_hints(retriever_tool.func)
    assert "query" in hints
    assert hints["query"] is str