fix: address review comments for nodeid prefix computation

- Handle AttributeError for site.getsitepackages() and site.getusersitepackages()
  which may not exist in some virtualenv configurations
- Add explanatory comments for bare OSError exception handlers
- Fix Windows compatibility in test by normalizing path separators

Co-authored-by: Cursor AI <ai@cursor.sh>
Co-authored-by: Anthropic Claude Opus 4 <claude@anthropic.com>

Author: 3 people

src/_pytest/nodes.py

@@ -578,17 +578,28 @@ def _get_site_packages_dirs() -> frozenset[Path]:
 
     dirs: set[Path] = set()
     # Standard site-packages
-    for sp in site.getsitepackages():
+    # getsitepackages() may not exist in some virtualenv configurations
+    try:
+        site_packages = site.getsitepackages()
+    except AttributeError:
+        site_packages = []
+    for sp in site_packages:
         try:
             dirs.add(Path(sp).resolve())
         except OSError:
+            # Path resolution can fail (deleted dir, permission issues, etc.)
             pass
     # User site-packages
-    user_site = site.getusersitepackages()
+    # getusersitepackages() may not exist in some virtualenv configurations
+    try:
+        user_site = site.getusersitepackages()
+    except AttributeError:
+        user_site = None
     if user_site:
         try:
             dirs.add(Path(user_site).resolve())
         except OSError:
+            # Path resolution can fail (deleted dir, permission issues, etc.)
             pass
     return frozenset(dirs)
 

testing/test_nodes.py

@@ -1,6 +1,7 @@
 # mypy: allow-untyped-defs
 from __future__ import annotations
 
+import os
 from pathlib import Path
 import re
 import warnings
@@ -289,7 +290,8 @@ def test_compute_nodeid_far_away_absolute(self, tmp_path: Path) -> None:
         )
 
         # Should use absolute path since it's more than 2 levels up
-        assert result == str(far_away)
+        # Use nodes.SEP for cross-platform compatibility (nodeids always use forward slashes)
+        assert result == str(far_away).replace(os.sep, nodes.SEP)
 
     def test_compute_nodeid_rootpath_itself(self, tmp_path: Path) -> None:
         """Test nodeid computation for rootpath itself returns empty string."""