Further cleanup in test_util (on new tests)

The main change here is to move the tests of how the HIDE_*
environment variables are treated up near the rmtree tests, since
they although the behaviors being tested are separate, they are
conceptually related, and also not entirely independent in that
they both involve the HIDE_WINDOWS_KNOWN_ERRORS attribute.

Other changes are mostly to formatting.

test/test_util.py

@@ -87,7 +87,14 @@ def test_rmtree_deletes_nested_dir_with_files(self):
             td = pathlib.Path(parent, "testdir")
             for d in td, td / "q", td / "s":
                 d.mkdir()
-            for f in td / "p", td / "q" / "w", td / "q" / "x", td / "r", td / "s" / "y", td / "s" / "z":
+            for f in (
+                td / "p",
+                td / "q" / "w",
+                td / "q" / "x",
+                td / "r",
+                td / "s" / "y",
+                td / "s" / "z",
+            ):
                 f.write_bytes(b"")
 
             try:
@@ -97,7 +104,10 @@ def test_rmtree_deletes_nested_dir_with_files(self):
 
             self.assertFalse(td.exists())
 
-    @skipIf(sys.platform == "cygwin", "Cygwin can't set the permissions that make the test meaningful.")
+    @skipIf(
+        sys.platform == "cygwin",
+        "Cygwin can't set the permissions that make the test meaningful.",
+    )
     def test_rmtree_deletes_dir_with_readonly_files(self):
         # Automatically works on Unix, but requires special handling on Windows.
         # Not to be confused with what _tmpdir_to_force_permission_error sets up (see below).
@@ -117,7 +127,7 @@ def test_rmtree_deletes_dir_with_readonly_files(self):
             self.assertFalse(td.exists())
 
     def test_rmtree_can_wrap_exceptions(self):
-        """Our rmtree wraps PermissionError when HIDE_WINDOWS_KNOWN_ERRORS is true."""
+        """rmtree wraps PermissionError when HIDE_WINDOWS_KNOWN_ERRORS is true."""
         with _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
@@ -135,19 +145,58 @@ def test_rmtree_can_wrap_exceptions(self):
         (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."""
+        """rmtree doesn't wrap non-PermissionError, nor if 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(
+                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}")
 
+    @ddt.data("HIDE_WINDOWS_KNOWN_ERRORS", "HIDE_WINDOWS_FREEZE_ERRORS")
+    def test_env_vars_for_windows_tests(self, name):
+        def run_parse(value):
+            command = [
+                sys.executable,
+                "-c",
+                f"from git.util import {name}; print(repr({name}))",
+            ]
+            output = subprocess.check_output(
+                command,
+                env=None if value is None else dict(os.environ, **{name: value}),
+                text=True,
+            )
+            return ast.literal_eval(output)
+
+        for env_var_value, expected_truth_value in (
+            (None, os.name == "nt"),  # True on Windows when the environment variable is unset.
+            ("", False),
+            (" ", False),
+            ("0", False),
+            ("1", os.name == "nt"),
+            ("false", False),
+            ("true", os.name == "nt"),
+            ("False", False),
+            ("True", os.name == "nt"),
+            ("no", False),
+            ("yes", os.name == "nt"),
+            ("NO", False),
+            ("YES", os.name == "nt"),
+            (" no  ", False),
+            (" yes  ", os.name == "nt"),
+        ):
+            with self.subTest(env_var_value=env_var_value):
+                self.assertIs(run_parse(env_var_value), expected_truth_value)
+
     _norm_cygpath_pairs = (
         (R"foo\bar", "foo/bar"),
         (R"foo/bar", "foo/bar"),
@@ -504,38 +553,3 @@ def test_remove_password_from_command_line(self):
 
         assert cmd_4 == remove_password_if_present(cmd_4)
         assert cmd_5 == remove_password_if_present(cmd_5)
-
-    @ddt.data("HIDE_WINDOWS_KNOWN_ERRORS", "HIDE_WINDOWS_FREEZE_ERRORS")
-    def test_env_vars_for_windows_tests(self, name):
-        def run_parse(value):
-            command = [
-                sys.executable,
-                "-c",
-                f"from git.util import {name}; print(repr({name}))",
-            ]
-            output = subprocess.check_output(
-                command,
-                env=None if value is None else dict(os.environ, **{name: value}),
-                text=True,
-            )
-            return ast.literal_eval(output)
-
-        for env_var_value, expected_truth_value in (
-            (None, os.name == "nt"),  # True on Windows when the environment variable is unset.
-            ("", False),
-            (" ", False),
-            ("0", False),
-            ("1", os.name == "nt"),
-            ("false", False),
-            ("true", os.name == "nt"),
-            ("False", False),
-            ("True", os.name == "nt"),
-            ("no", False),
-            ("yes", os.name == "nt"),
-            ("NO", False),
-            ("YES", os.name == "nt"),
-            (" no  ", False),
-            (" yes  ", os.name == "nt"),
-        ):
-            with self.subTest(env_var_value=env_var_value):
-                self.assertIs(run_parse(env_var_value), expected_truth_value)