typing: fix missing (#121)

* typing: fix missing a return type
* skipif for DDP

Author: Borda

src/litmodels/io/utils.py

@@ -1,5 +1,6 @@
 import os
 import pickle
+from collections.abc import Iterator
 from contextlib import contextmanager
 from pathlib import Path
 from typing import Any, Union
@@ -9,7 +10,7 @@
 
 
 @contextmanager
-def _suppress_os_stderr():
+def _suppress_os_stderr() -> Iterator[None]:
     devnull_fd = os.open(os.devnull, os.O_WRONLY)
     old_stderr_fd = os.dup(2)
     os.dup2(devnull_fd, 2)  # redirect stderr (fd 2) to /dev/null

tests/integrations/test_real_cloud.py

@@ -208,6 +208,7 @@ def test_lightning_plain_resume(trainer_method, registry, importing, in_studio,
     ],
 )
 @pytest.mark.cloud
+@pytest.mark.skipif(platform.system() != "Linux", reason="Only Linux is supported for DDP")
 def test_lightning_checkpoint_ddp(importing, tmp_path):
     if importing == "lightning":
         from lightning import Trainer