test: Simplify submodule path simulation and verify metadata removal

rubber stamp
<!-- agent -->
The Python 3.7 Windows path simulation wrapped the entire os.path module
in Mock. On Windows, all six simulated removal cases hit sharing
violations that the default error handling converted into skipped tests.

Use a SimpleNamespace copy of the path module and replace only realpath
with abspath. Patch only the submodule module's osp binding so pathlib
keeps its own resolver and other path operations remain ordinary calls.
This retains Python 3.7 compatibility and allows the removal cases to run
successfully without Windows permission-error suppression.

Before removing a submodule, resolve and verify its metadata directory,
then assert that removal deletes it as well as the checkout. Checking only
the checkout could miss metadata left behind through a directory symlink.

Validation: all 57 focused submodule compatibility and process-cleanup
tests passed on Windows with Python 3.10 and HIDE_WINDOWS_KNOWN_ERRORS=0.
Ruff 0.16.5 lint and formatting checks and git diff --check passed.
Native Python 3.7 was unavailable; its realpath behavior is simulated.

Assisted-by: GPT 6.0
Co-authored-by: GPT 6.0 <codex@openai.com>

Author: Byron

test/test_submodule.py

@@ -9,6 +9,7 @@
 import shutil
 import sys
 import tempfile
+from types import SimpleNamespace
 from unittest import mock, skipUnless
 
 import pytest
@@ -316,8 +317,9 @@ def test_submodule_allows_symlink_above_worktree(
 def metadata_realpath(request):
     """Model Python 3.7 on Windows without altering pathlib's own resolver."""
     if request.param:
-        with mock.patch("git.objects.submodule.base.osp", wraps=osp) as paths:
-            paths.realpath.side_effect = osp.abspath
+        paths = SimpleNamespace(**vars(osp))
+        paths.realpath = osp.abspath
+        with mock.patch("git.objects.submodule.base.osp", paths):
             yield
     else:
         yield
@@ -361,7 +363,7 @@ def test_submodule_allows_existing_metadata_symlinks(
 
     Cover linked metadata directories, gitfiles, configs, and internal aliases.
     Update, move, and rename must retain a usable checkout; forced removal must
-    still remove it.
+    still remove both the checkout and the resolved metadata directory.
     """
     sm = movable_submodule
     sm.rename("nested/module")
@@ -387,8 +389,11 @@ def test_submodule_allows_existing_metadata_symlinks(
     sm.repo.git.config("--file", str(modules / "nested/module/config"), "core.worktree", str(root / "module"))
     assert sm.module_exists()
     if operation == "remove":
+        metadata_dir = (modules / "nested/module").resolve()
+        assert metadata_dir.is_dir()
         sm.remove(force=True)
         assert not (root / "module").exists()
+        assert not metadata_dir.exists()
         return
     if operation == "update":
         sm.update()