chore(core): fix some ruff preview rules (#32785)

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

Author: cbornet

libs/core/langchain_core/_api/deprecation.py

@@ -361,16 +361,17 @@ def finalize(wrapper: Callable[..., Any], new_doc: str) -> T:
         # Modify the docstring to include a deprecation notice.
         if (
             _alternative
-            and _alternative.split(".")[-1].lower() == _alternative.split(".")[-1]
+            and _alternative.rsplit(".", maxsplit=1)[-1].lower()
+            == _alternative.rsplit(".", maxsplit=1)[-1]
         ):
             _alternative = f":meth:`~{_alternative}`"
         elif _alternative:
             _alternative = f":class:`~{_alternative}`"
 
         if (
             _alternative_import
-            and _alternative_import.split(".")[-1].lower()
-            == _alternative_import.split(".")[-1]
+            and _alternative_import.rsplit(".", maxsplit=1)[-1].lower()
+            == _alternative_import.rsplit(".", maxsplit=1)[-1]
         ):
             _alternative_import = f":meth:`~{_alternative_import}`"
         elif _alternative_import:
@@ -474,7 +475,7 @@ def warn_deprecated(
     if not message:
         message = ""
         package_ = (
-            package or name.split(".")[0].replace("_", "-")
+            package or name.split(".", maxsplit=1)[0].replace("_", "-")
             if "." in name
             else "LangChain"
         )
@@ -493,7 +494,7 @@ def warn_deprecated(
                 message += f" and will be removed {removal}"
 
         if alternative_import:
-            alt_package = alternative_import.split(".")[0].replace("_", "-")
+            alt_package = alternative_import.split(".", maxsplit=1)[0].replace("_", "-")
             if alt_package == package_:
                 message += f". Use {alternative_import} instead."
             else:

libs/core/langchain_core/embeddings/fake.py

@@ -119,7 +119,8 @@ def _get_embedding(self, seed: int) -> list[float]:
         rng = np.random.default_rng(seed)
         return list(rng.normal(size=self.size))
 
-    def _get_seed(self, text: str) -> int:
+    @staticmethod
+    def _get_seed(text: str) -> int:
         """Get a seed for the random generator, using the hash of the text."""
         return int(hashlib.sha256(text.encode("utf-8")).hexdigest(), 16) % 10**8
 

libs/core/langchain_core/language_models/chat_models.py

@@ -148,8 +148,6 @@ def _format_for_tracing(messages: list[BaseMessage]) -> list[BaseMessage]:
                             "type": key,
                             key: block[key],
                         }
-                    else:
-                        pass
         messages_to_trace.append(message_to_trace)
 
     return messages_to_trace

libs/core/langchain_core/messages/ai.py

@@ -352,10 +352,7 @@ def add_chunk_to_invalid_tool_calls(chunk: ToolCallChunk) -> None:
 
         for chunk in self.tool_call_chunks:
             try:
-                if chunk["args"] is not None and chunk["args"] != "":
-                    args_ = parse_partial_json(chunk["args"])
-                else:
-                    args_ = {}
+                args_ = parse_partial_json(chunk["args"]) if chunk["args"] else {}
                 if isinstance(args_, dict):
                     tool_calls.append(
                         create_tool_call(

libs/core/langchain_core/messages/base.py

@@ -179,9 +179,7 @@ def merge_content(
         elif merged and isinstance(merged[-1], str):
             merged[-1] += content
         # If second content is an empty string, treat as a no-op
-        elif content == "":
-            pass
-        else:
+        elif content:
             # Otherwise, add the second content as a new element of the list
             merged.append(content)
     return merged

libs/core/langchain_core/output_parsers/json.py

@@ -46,11 +46,13 @@ class JsonOutputParser(BaseCumulativeTransformOutputParser[Any]):
     def _diff(self, prev: Optional[Any], next: Any) -> Any:
         return jsonpatch.make_patch(prev, next).patch
 
-    def _get_schema(self, pydantic_object: type[TBaseModel]) -> dict[str, Any]:
+    @staticmethod
+    def _get_schema(pydantic_object: type[TBaseModel]) -> dict[str, Any]:
         if issubclass(pydantic_object, pydantic.BaseModel):
             return pydantic_object.model_json_schema()
         return pydantic_object.schema()
 
+    @override
     def parse_result(self, result: list[Generation], *, partial: bool = False) -> Any:
         """Parse the result of an LLM call to a JSON object.
 

libs/core/langchain_core/output_parsers/list.py

@@ -155,13 +155,15 @@ def get_lc_namespace(cls) -> list[str]:
         """
         return ["langchain", "output_parsers", "list"]
 
+    @override
     def get_format_instructions(self) -> str:
         """Return the format instructions for the comma-separated list output."""
         return (
             "Your response should be a list of comma separated values, "
             "eg: `foo, bar, baz` or `foo,bar,baz`"
         )
 
+    @override
     def parse(self, text: str) -> list[str]:
         """Parse the output of an LLM call.
 
@@ -224,6 +226,7 @@ class MarkdownListOutputParser(ListOutputParser):
     pattern: str = r"^\s*[-*]\s([^\n]+)$"
     """The pattern to match a Markdown list item."""
 
+    @override
     def get_format_instructions(self) -> str:
         """Return the format instructions for the Markdown list output."""
         return "Your response should be a markdown list, eg: `- foo\n- bar\n- baz`"

libs/core/langchain_core/output_parsers/string.py

@@ -1,5 +1,7 @@
 """String output parser."""
 
+from typing_extensions import override
+
 from langchain_core.output_parsers.transform import BaseTransformOutputParser
 
 
@@ -29,6 +31,7 @@ def _type(self) -> str:
         """Return the output parser type for serialization."""
         return "default"
 
+    @override
     def parse(self, text: str) -> str:
         """Returns the input text with no changes."""
         return text

libs/core/langchain_core/prompts/base.py

@@ -210,7 +210,7 @@ def invoke(
         if self.metadata:
             config["metadata"] = {**config["metadata"], **self.metadata}
         if self.tags:
-            config["tags"] = config["tags"] + self.tags
+            config["tags"] += self.tags
         return self._call_with_config(
             self._format_prompt_with_error_handling,
             input,

libs/core/langchain_core/prompts/string.py

@@ -166,7 +166,7 @@ def mustache_schema(
                 prefix = section_stack.pop()
         elif type_ in {"section", "inverted section"}:
             section_stack.append(prefix)
-            prefix = prefix + tuple(key.split("."))
+            prefix += tuple(key.split("."))
             fields[prefix] = False
         elif type_ in {"variable", "no escape"}:
             fields[prefix + tuple(key.split("."))] = True