Fix Python E2E test flakiness and missing pytest-timeout (#391)

- Add ignore_errors=True to shutil.rmtree() in test cleanup to handle
  race conditions where files are still being written by background processes
- Add missing_ok=True to unlink() for same reason
- Add pytest-timeout to dev dependencies (fixes warning about unknown mark)

Author: SteveSandersonMS

python/e2e/testharness/context.py

@@ -100,16 +100,18 @@ async def configure_for_test(self, test_file: str, test_name: str):
             await self._proxy.configure(abs_snapshot_path, self.work_dir)
 
         # Clear temp directories between tests (but leave them in place)
+        # Use ignore_errors=True to handle race conditions where files may still
+        # be written by background processes during cleanup
         for item in Path(self.home_dir).iterdir():
             if item.is_dir():
-                shutil.rmtree(item)
+                shutil.rmtree(item, ignore_errors=True)
             else:
-                item.unlink()
+                item.unlink(missing_ok=True)
         for item in Path(self.work_dir).iterdir():
             if item.is_dir():
-                shutil.rmtree(item)
+                shutil.rmtree(item, ignore_errors=True)
             else:
-                item.unlink()
+                item.unlink(missing_ok=True)
 
     def get_env(self) -> dict:
         """Return environment variables configured for isolated testing."""

python/pyproject.toml

@@ -42,6 +42,7 @@ dev = [
     "ty>=0.0.2",
     "pytest>=7.0.0",
     "pytest-asyncio>=0.21.0",
+    "pytest-timeout>=2.0.0",
     "httpx>=0.24.0",
 ]