core, tests: more tolerant _aget_relevant_documents function (#28462)

libs/core/langchain_core/retrievers.py

@@ -27,7 +27,7 @@ from inspect import signature
 from typing import TYPE_CHECKING, Any, Optional
 
 from pydantic import ConfigDict
-from typing_extensions import TypedDict
+from typing_extensions import Self, TypedDict
 
 from langchain_core._api import deprecated
 from langchain_core.documents import Document
@@ -180,6 +180,18 @@ class BaseRetriever(RunnableSerializable[RetrieverInput, RetrieverOutput], ABC):
             cls._aget_relevant_documents = aswap  # type: ignore[assignment]
         parameters = signature(cls._get_relevant_documents).parameters
         cls._new_arg_supported = parameters.get("run_manager") is not None
+        if (
+            not cls._new_arg_supported
+            and cls._aget_relevant_documents == BaseRetriever._aget_relevant_documents
+        ):
+            # we need to tolerate no run_manager in _aget_relevant_documents signature
+            async def _aget_relevant_documents(
+                self: Self, query: str
+            ) -> list[Document]:
+                return await run_in_executor(None, self._get_relevant_documents, query)  # type: ignore
+
+            cls._aget_relevant_documents = _aget_relevant_documents  # type: ignore[assignment]
+
         # If a V1 retriever broke the interface and expects additional arguments
         cls._expects_other_args = (
             len(set(parameters.keys()) - {"self", "query", "run_manager"}) > 0