core: Add ruff rules PTH (pathlib) (#29338)

See https://docs.astral.sh/ruff/rules/#flake8-use-pathlib-pth

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

libs/core/tests/unit_tests/prompts/test_prompt.py

@@ -354,7 +354,7 @@ def test_prompt_from_file_with_partial_variables() -> None:
     template = "This is a {foo} test {bar}."
     partial_variables = {"bar": "baz"}
     # when
-    with mock.patch("builtins.open", mock.mock_open(read_data=template)):
+    with mock.patch("pathlib.Path.open", mock.mock_open(read_data=template)):
         prompt = PromptTemplate.from_file(
             "mock_file_name", partial_variables=partial_variables
         )

libs/core/tests/unit_tests/test_imports.py

@@ -1,20 +1,17 @@
 import concurrent.futures
-import glob
 import importlib
 import subprocess
 from pathlib import Path
 
 
 def test_importable_all() -> None:
-    for path in glob.glob("../core/langchain_core/*"):
-        relative_path = Path(path).parts[-1]
-        if relative_path.endswith(".typed"):
-            continue
-        module_name = relative_path.split(".")[0]
-        module = importlib.import_module("langchain_core." + module_name)
-        all_ = getattr(module, "__all__", [])
-        for cls_ in all_:
-            getattr(module, cls_)
+    for path in Path("../core/langchain_core/").glob("*"):
+        module_name = path.stem
+        if not module_name.startswith(".") and path.suffix != ".typed":
+            module = importlib.import_module("langchain_core." + module_name)
+            all_ = getattr(module, "__all__", [])
+            for cls_ in all_:
+                getattr(module, cls_)
 
 
 def try_to_import(module_name: str) -> tuple[int, str]:
@@ -37,12 +34,10 @@ def test_importable_all_via_subprocess() -> None:
           for one sequence of imports but not another.
     """
     module_names = []
-    for path in glob.glob("../core/langchain_core/*"):
-        relative_path = Path(path).parts[-1]
-        if relative_path.endswith(".typed"):
-            continue
-        module_name = relative_path.split(".")[0]
-        module_names.append(module_name)
+    for path in Path("../core/langchain_core/").glob("*"):
+        module_name = path.stem
+        if not module_name.startswith(".") and path.suffix != ".typed":
+            module_names.append(module_name)
 
     with concurrent.futures.ThreadPoolExecutor(max_workers=10) as executor:
         futures = [