style(langchain): add ruff rule RUF012 (#34497)

Co-authored-by: Mason Daugherty <mason@langchain.dev>
Co-authored-by: Mason Daugherty <github@mdrxy.com>

libs/langchain_v1/langchain/agents/middleware/types.py

@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from collections.abc import Awaitable, Callable
+from collections.abc import Awaitable, Callable, Sequence
 from dataclasses import dataclass, field, replace
 from inspect import iscoroutinefunction
 from typing import (
@@ -338,7 +338,7 @@ class AgentMiddleware(Generic[StateT, ContextT]):
     state_schema: type[StateT] = cast("type[StateT]", AgentState)
     """The schema for state passed to the middleware nodes."""
 
-    tools: list[BaseTool]
+    tools: Sequence[BaseTool]
     """Additional tools registered by the middleware."""
 
     @property

libs/langchain_v1/pyproject.toml

@@ -112,7 +112,6 @@ ignore = [
     "FIX002",  # Line contains TODO
     "PERF203", # Rarely useful
     "PLR09",   # Too many something (arg, statements, etc)
-    "RUF012",  # Doesn't play well with Pydantic
     "TD002",   # Missing author in TODO
     "TD003",   # Missing issue link in TODO
 

libs/langchain_v1/tests/unit_tests/agents/middleware/core/test_tools.py

@@ -293,7 +293,7 @@ def test_middleware_with_additional_tools() -> None:
         return "middleware"
 
     class ToolProvidingMiddleware(AgentMiddleware):
-        tools = [middleware_tool]
+        tools = (middleware_tool,)
 
     # Model calls the middleware-provided tool
     model = FakeToolCallingModel(

libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_summarization.py

@@ -31,7 +31,7 @@ class ProfileChatModel(BaseChatModel):
     def _generate(self, messages, **kwargs):  # type: ignore[no-untyped-def]
         return ChatResult(generations=[ChatGeneration(message=AIMessage(content="Summary"))])
 
-    profile: ModelProfile | None = {"max_input_tokens": 1000}
+    profile: ModelProfile | None = ModelProfile(max_input_tokens=1000)
 
     @property
     def _llm_type(self) -> str:

libs/langchain_v1/tests/unit_tests/agents/middleware/implementations/test_tool_emulator.py

@@ -1,7 +1,7 @@
 """Unit tests for tool emulator middleware."""
 
 import typing
-from collections.abc import Callable
+from collections.abc import Callable, Sequence
 from itertools import cycle
 from typing import Any, Literal
 
@@ -86,7 +86,7 @@ class FakeModel(GenericFakeChatModel):
 class FakeEmulatorModel(BaseChatModel):
     """Fake model for emulating tool responses."""
 
-    responses: list[str] = ["Emulated response"]
+    responses: Sequence[str] = ("Emulated response",)
     response_index: int = 0
 
     def _generate(

libs/langchain_v1/tests/unit_tests/agents/test_response_format.py

@@ -776,7 +776,7 @@ class TestDynamicModelWithResponseFormat:
         # Custom model that we'll use to test whether the tool strategy is applied
         # correctly at runtime.
         class CustomModel(GenericFakeChatModel):
-            tool_bindings: list[Any] = []
+            tool_bindings: list[Any] = Field(default_factory=list)
 
             def bind_tools(
                 self,