core: Add ruff rules ANN (type annotations) (#29271)

See https://docs.astral.sh/ruff/rules/#flake8-annotations-ann
The interest compared to only mypy is that ruff is very fast at
detecting missing annotations.

ANN101 and ANN102 are deprecated so we ignore them 
ANN401 (no Any type) ignored to be in sync with mypy config

---------

Co-authored-by: ccurme <chester.curme@gmail.com>

libs/core/langchain_core/_api/beta_decorator.py

@@ -156,28 +156,36 @@ def beta(
             class _BetaProperty(property):
                 """A beta property."""
 
-                def __init__(self, fget=None, fset=None, fdel=None, doc=None):
+                def __init__(
+                    self,
+                    fget: Union[Callable[[Any], Any], None] = None,
+                    fset: Union[Callable[[Any, Any], None], None] = None,
+                    fdel: Union[Callable[[Any], None], None] = None,
+                    doc: Union[str, None] = None,
+                ) -> None:
                     super().__init__(fget, fset, fdel, doc)
                     self.__orig_fget = fget
                     self.__orig_fset = fset
                     self.__orig_fdel = fdel
 
-                def __get__(self, instance, owner=None):
+                def __get__(
+                    self, instance: Any, owner: Union[type, None] = None
+                ) -> Any:
                     if instance is not None or owner is not None:
                         emit_warning()
                     return self.fget(instance)
 
-                def __set__(self, instance, value):
+                def __set__(self, instance: Any, value: Any) -> None:
                     if instance is not None:
                         emit_warning()
                     return self.fset(instance, value)
 
-                def __delete__(self, instance):
+                def __delete__(self, instance: Any) -> None:
                     if instance is not None:
                         emit_warning()
                     return self.fdel(instance)
 
-                def __set_name__(self, owner, set_name):
+                def __set_name__(self, owner: Union[type, None], set_name: str) -> None:
                     nonlocal _name
                     if _name == "<lambda>":
                         _name = set_name

libs/core/langchain_core/_api/deprecation.py

@@ -270,28 +270,40 @@ def deprecated(
             class _DeprecatedProperty(property):
                 """A deprecated property."""
 
-                def __init__(self, fget=None, fset=None, fdel=None, doc=None):  # type: ignore[no-untyped-def]
+                def __init__(
+                    self,
+                    fget: Union[Callable[[Any], Any], None] = None,
+                    fset: Union[Callable[[Any, Any], None], None] = None,
+                    fdel: Union[Callable[[Any], None], None] = None,
+                    doc: Union[str, None] = None,
+                ) -> None:
                     super().__init__(fget, fset, fdel, doc)
                     self.__orig_fget = fget
                     self.__orig_fset = fset
                     self.__orig_fdel = fdel
 
-                def __get__(self, instance, owner=None):  # type: ignore[no-untyped-def]
+                def __get__(
+                    self, instance: Any, owner: Union[type, None] = None
+                ) -> Any:
                     if instance is not None or owner is not None:
                         emit_warning()
+                    if self.fget is None:
+                        return None
                     return self.fget(instance)
 
-                def __set__(self, instance, value):  # type: ignore[no-untyped-def]
+                def __set__(self, instance: Any, value: Any) -> None:
                     if instance is not None:
                         emit_warning()
-                    return self.fset(instance, value)
+                    if self.fset is not None:
+                        self.fset(instance, value)
 
-                def __delete__(self, instance):  # type: ignore[no-untyped-def]
+                def __delete__(self, instance: Any) -> None:
                     if instance is not None:
                         emit_warning()
-                    return self.fdel(instance)
+                    if self.fdel is not None:
+                        self.fdel(instance)
 
-                def __set_name__(self, owner, set_name):  # type: ignore[no-untyped-def]
+                def __set_name__(self, owner: Union[type, None], set_name: str) -> None:
                     nonlocal _name
                     if _name == "<lambda>":
                         _name = set_name

libs/core/langchain_core/runnables/base.py

@@ -4641,7 +4641,7 @@ class RunnableLambda(Runnable[Input, Output]):
                     )
 
             @wraps(func)
-            async def f(*args, **kwargs):  # type: ignore[no-untyped-def]
+            async def f(*args: Any, **kwargs: Any) -> Any:
                 return await run_in_executor(config, func, *args, **kwargs)
 
             afunc = f
@@ -4889,7 +4889,7 @@ class RunnableLambda(Runnable[Input, Output]):
                 )
 
             @wraps(func)
-            async def f(*args, **kwargs):  # type: ignore[no-untyped-def]
+            async def f(*args: Any, **kwargs: Any) -> Any:
                 return await run_in_executor(config, func, *args, **kwargs)
 
             afunc = f

libs/core/langchain_core/utils/utils.py

@@ -6,7 +6,7 @@ import functools
 import importlib
 import os
 import warnings
-from collections.abc import Sequence
+from collections.abc import Iterator, Sequence
 from importlib.metadata import version
 from typing import Any, Callable, Optional, Union, overload
 
@@ -73,7 +73,7 @@ def raise_for_status_with_text(response: Response) -> None:
 
 
 @contextlib.contextmanager
-def mock_now(dt_value):  # type: ignore
+def mock_now(dt_value: datetime.datetime) -> Iterator[type]:
     """Context manager for mocking out datetime.now() in unit tests.
 
     Args:
@@ -91,9 +91,9 @@ def mock_now(dt_value):  # type: ignore
         """Mock datetime.datetime.now() with a fixed datetime."""
 
         @classmethod
-        def now(cls):  # type: ignore
+        def now(cls, tz: Union[datetime.tzinfo, None] = None) -> "MockDateTime":
             # Create a copy of dt_value.
-            return datetime.datetime(
+            return MockDateTime(
                 dt_value.year,
                 dt_value.month,
                 dt_value.day,
@@ -105,11 +105,11 @@ def mock_now(dt_value):  # type: ignore
             )
 
     real_datetime = datetime.datetime
-    datetime.datetime = MockDateTime
+    datetime.datetime = MockDateTime  # type: ignore[misc]
     try:
         yield datetime.datetime
     finally:
-        datetime.datetime = real_datetime
+        datetime.datetime = real_datetime  # type: ignore[misc]
 
 
 def guard_import(

libs/core/pyproject.toml

@@ -77,8 +77,10 @@ target-version = "py39"
 
 
 [tool.ruff.lint]
-select = [ "ASYNC", "B", "C4", "COM", "DJ", "E", "EM", "EXE", "F", "FLY", "FURB", "I", "ICN", "INT", "LOG", "N", "NPY", "PD", "PIE", "Q", "RSE", "S", "SIM", "SLOT", "T10", "T201", "TID", "TRY", "UP", "W", "YTT",]
-ignore = [ "COM812", "UP007", "S110", "S112",]
+select = [ "ANN", "ASYNC", "B", "C4", "COM", "DJ", "E", "EM", "EXE", "F", "FLY", "FURB", "I", "ICN", "INT", "LOG", "N", "NPY", "PD", "PIE", "Q", "RSE", "S", "SIM", "SLOT", "T10", "T201", "TID", "TRY", "UP", "W", "YTT",]
+ignore = [ "ANN401", "COM812", "UP007", "S110", "S112",]
+flake8-annotations.allow-star-arg-any = true
+flake8-annotations.mypy-init-return = true
 
 [tool.coverage.run]
 omit = [ "tests/*",]

libs/core/tests/unit_tests/runnables/test_runnable.py

@@ -567,7 +567,7 @@ def test_lambda_schemas(snapshot: SnapshotAssertion) -> None:
         "required": ["bye", "hello"],
     }
 
-    def get_value(input):  # type: ignore[no-untyped-def]
+    def get_value(input):  # type: ignore[no-untyped-def] # noqa: ANN001,ANN202
         return input["variable_name"]
 
     assert RunnableLambda(get_value).get_input_jsonschema() == {
@@ -577,7 +577,7 @@ def test_lambda_schemas(snapshot: SnapshotAssertion) -> None:
         "required": ["variable_name"],
     }
 
-    async def aget_value(input):  # type: ignore[no-untyped-def]
+    async def aget_value(input):  # type: ignore[no-untyped-def] # noqa: ANN001,ANN202
         return (input["variable_name"], input.get("another"))
 
     assert RunnableLambda(aget_value).get_input_jsonschema() == {
@@ -590,7 +590,7 @@ def test_lambda_schemas(snapshot: SnapshotAssertion) -> None:
         "required": ["another", "variable_name"],
     }
 
-    async def aget_values(input):  # type: ignore[no-untyped-def]
+    async def aget_values(input):  # type: ignore[no-untyped-def] # noqa: ANN001,ANN202
         return {
             "hello": input["variable_name"],
             "bye": input["variable_name"],

libs/core/tests/unit_tests/runnables/test_runnable_events_v2.py

@@ -9,6 +9,7 @@ from functools import partial
 from itertools import cycle
 from typing import (
     Any,
+    Callable,
     Optional,
     cast,
 )
@@ -1902,10 +1903,10 @@ async def test_runnable_with_message_history() -> None:
     # so we can raise them in this main thread
     raised_errors = []
 
-    def collect_errors(fn):  # type: ignore
+    def collect_errors(fn: Callable[..., Any]) -> Callable[..., Any]:
         nonlocal raised_errors
 
-        def _get_output_messages(*args, **kwargs):  # type: ignore
+        def _get_output_messages(*args: Any, **kwargs: Any) -> Any:
             try:
                 return fn(*args, **kwargs)
             except Exception as e:

libs/core/tests/unit_tests/runnables/test_tracing_interops.py

@@ -465,7 +465,7 @@ def test_tree_is_constructed(parent_type: Literal["ls", "lc"]) -> None:
         else:
 
             @RunnableLambda
-            def parent(_) -> str:  # type: ignore
+            def parent(_: Any) -> str:
                 return child.invoke("foo")
 
             tracer = LangChainTracer()

libs/core/tests/unit_tests/test_tools.py

@@ -2217,7 +2217,7 @@ def test_tool_args_schema_pydantic_v2_with_metadata() -> None:
         )
 
     @tool(args_schema=Foo)
-    def foo(x):  # type: ignore[no-untyped-def]
+    def foo(x) -> list[int]:  # type: ignore[no-untyped-def] # noqa: ANN001
         """Foo."""
         return x