Test situations git.util.rmtree shouldn't wrap

One of the new test cases fails, showing the bug where
git.util.rmtree wraps any exception in SkipTest when
HIDE_WINDOWS_KNOWN_ERRORS is true, even though the message it uses
(and its purpose) is specific to PermissionError.

The other new cases pass, because wrapping exceptions in SkipTest
rightly does not occur when HIDE_WINDOWS_KNOWN_ERRORS is false.

Author: EliahKagan

test/test_util.py

@@ -4,6 +4,7 @@
 # This module is part of GitPython and is released under
 # the BSD License: https://opensource.org/license/bsd-3-clause/
 
+import contextlib
 import os
 import pathlib
 import pickle
@@ -121,16 +122,31 @@ def test_rmtree_deletes_dir_with_readonly_files(self):
 
             self.assertFalse(td.exists())
 
-    @skipIf(sys.platform == "cygwin", "Cygwin can't set the permissions that make the test meaningful.")
-    @skipIf(sys.version_info < (3, 8), "In 3.7, TemporaryDirectory doesn't clean up after weird permissions.")
-    def test_rmtree_can_wrap_exceptions(self):
+    @staticmethod
+    @contextlib.contextmanager
+    def _tmpdir_to_force_permission_error():
+        if sys.platform == "cygwin":
+            raise SkipTest("Cygwin can't set the permissions that make the test meaningful.")
+        if sys.version_info < (3, 8):
+            raise SkipTest("In 3.7, TemporaryDirectory doesn't clean up after weird permissions.")
+
         with tempfile.TemporaryDirectory() as parent:
             td = pathlib.Path(parent, "testdir")
             td.mkdir()
             (td / "x").write_bytes(b"")
             (td / "x").chmod(stat.S_IRUSR)  # Set up PermissionError on Windows.
             td.chmod(stat.S_IRUSR | stat.S_IXUSR)  # Set up PermissionError on Unix.
+            yield td
 
+    @staticmethod
+    @contextlib.contextmanager
+    def _tmpdir_for_file_not_found():
+        with tempfile.TemporaryDirectory() as parent:
+            yield pathlib.Path(parent, "testdir")  # It is deliberately never created.
+
+    def test_rmtree_can_wrap_exceptions(self):
+        """Our rmtree wraps PermissionError when HIDE_WINDOWS_KNOWN_ERRORS is true."""
+        with self._tmpdir_to_force_permission_error() as td:
             # 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.
@@ -141,6 +157,25 @@ def test_rmtree_can_wrap_exceptions(self):
                     with self.assertRaises(SkipTest):
                         rmtree(td)
 
+    @ddt.data(
+        (False, PermissionError, _tmpdir_to_force_permission_error),
+        (False, FileNotFoundError, _tmpdir_for_file_not_found),
+        (True, FileNotFoundError, _tmpdir_for_file_not_found),
+    )
+    def test_rmtree_does_not_wrap_unless_called_for(self, case):
+        """Our rmtree doesn't wrap non-PermissionError, nor when HIDE_WINDOWS_KNOWN_ERRORS is false."""
+        hide_windows_known_errors, exception_type, tmpdir_context_factory = case
+
+        with tmpdir_context_factory() as td:
+            # See comments in test_rmtree_can_wrap_exceptions regarding the patching done here.
+            with mock.patch.object(sys.modules["git.util"], "HIDE_WINDOWS_KNOWN_ERRORS", hide_windows_known_errors):
+                with mock.patch.object(os, "chmod"), mock.patch.object(pathlib.Path, "chmod"):
+                    with self.assertRaises(exception_type):
+                        try:
+                            rmtree(td)
+                        except SkipTest as ex:
+                            self.fail(f"rmtree unexpectedly attempts skip: {ex!r}")
+
     # FIXME: Mark only the /proc-prefixing cases xfail, somehow (or fix them).
     @pytest.mark.xfail(
         reason="Many return paths prefixed /proc/cygdrive instead.",