Extract some shared patching code to a helper

Because of how it is parameterized, but only in some of the test
cases that use it, making this a pytest fixture would be cumbersome
without further refactoring, so this is a helper method instead.

(It may be feasible to further refactor the test suite to improve
this more.)

This also removes a type annotation from a test method. It may
eventually be helpful to add annotations, in which case that would
come back along with others (if that test still exists in this
form), but it's the only test with such an annotation in this
test class, and the annotation had been added accidentally.

Author: EliahKagan

test/test_util.py

@@ -109,7 +109,7 @@ def test_deletes_dir_with_readonly_files(self, tmp_path):
         sys.platform == "cygwin",
         reason="Cygwin can't set the permissions that make the test meaningful.",
     )
-    def test_avoids_changing_permissions_outside_tree(self, tmp_path: pathlib.Path):
+    def test_avoids_changing_permissions_outside_tree(self, tmp_path):
         # Automatically works on Windows, but on Unix requires either special handling
         # or refraining from attempting to fix PermissionError by making chmod calls.
 
@@ -134,22 +134,24 @@ def test_avoids_changing_permissions_outside_tree(self, tmp_path: pathlib.Path):
         new_mode = (dir1 / "file").stat().st_mode
         assert old_mode == new_mode, f"Should stay {old_mode:#o}, became {new_mode:#o}."
 
-    @pytest.mark.skipif(
-        os.name != "nt",
-        reason="PermissionError is only ever wrapped on Windows",
-    )
-    def test_wraps_perm_error_if_enabled(self, mocker, permission_error_tmpdir):
-        """rmtree wraps PermissionError on Windows when HIDE_WINDOWS_KNOWN_ERRORS is true."""
+    def _patch_for_wrapping_test(self, mocker, hide_windows_known_errors):
         # Access the module through sys.modules so it is unambiguous which module's
         # attribute we patch: the original git.util, not git.index.util even though
         # git.index.util "replaces" git.util and is what "import git.util" gives us.
-        mocker.patch.object(sys.modules["git.util"], "HIDE_WINDOWS_KNOWN_ERRORS", True)
+        mocker.patch.object(sys.modules["git.util"], "HIDE_WINDOWS_KNOWN_ERRORS", hide_windows_known_errors)
 
-        # Disable common chmod functions so the callback can never fix the problem.
+        # Disable common chmod functions so the callback can't fix a PermissionError.
         mocker.patch.object(os, "chmod")
         mocker.patch.object(pathlib.Path, "chmod")
 
-        # Now we can see how an intractable PermissionError is treated.
+    @pytest.mark.skipif(
+        os.name != "nt",
+        reason="PermissionError is only ever wrapped on Windows",
+    )
+    def test_wraps_perm_error_if_enabled(self, mocker, permission_error_tmpdir):
+        """rmtree wraps PermissionError on Windows when HIDE_WINDOWS_KNOWN_ERRORS is true."""
+        self._patch_for_wrapping_test(mocker, True)
+
         with pytest.raises(SkipTest):
             rmtree(permission_error_tmpdir)
 
@@ -166,10 +168,7 @@ def test_wraps_perm_error_if_enabled(self, mocker, permission_error_tmpdir):
     )
     def test_does_not_wrap_perm_error_unless_enabled(self, mocker, permission_error_tmpdir, hide_windows_known_errors):
         """rmtree does not wrap PermissionError on non-Windows systems or when HIDE_WINDOWS_KNOWN_ERRORS is false."""
-        # See comments in test_wraps_perm_error_if_enabled for details about patching.
-        mocker.patch.object(sys.modules["git.util"], "HIDE_WINDOWS_KNOWN_ERRORS", hide_windows_known_errors)
-        mocker.patch.object(os, "chmod")
-        mocker.patch.object(pathlib.Path, "chmod")
+        self._patch_for_wrapping_test(mocker, hide_windows_known_errors)
 
         with pytest.raises(PermissionError):
             try:
@@ -180,11 +179,7 @@ def test_does_not_wrap_perm_error_unless_enabled(self, mocker, permission_error_
     @pytest.mark.parametrize("hide_windows_known_errors", [False, True])
     def test_does_not_wrap_other_errors(self, tmp_path, mocker, hide_windows_known_errors):
         file_not_found_tmpdir = tmp_path / "testdir"  # It is deliberately never created.
-
-        # See comments in test_wraps_perm_error_if_enabled for details about patching.
-        mocker.patch.object(sys.modules["git.util"], "HIDE_WINDOWS_KNOWN_ERRORS", hide_windows_known_errors)
-        mocker.patch.object(os, "chmod")
-        mocker.patch.object(pathlib.Path, "chmod")
+        self._patch_for_wrapping_test(mocker, hide_windows_known_errors)
 
         with pytest.raises(FileNotFoundError):
             try: