diff --git a/test/test_util.py b/test/test_util.py
@@ -46,7 +46,7 @@ def permission_error_tmpdir(tmp_path):
    """Fixture to test permissions errors in situations where they are not overcome."""
    td = tmp_path / "testdir"
    td.mkdir()
-    (td / "x").write_bytes(b"")

    # Set up PermissionError on Windows, where we can't delete read-only files.
    (td / "x").chmod(stat.S_IRUSR)
@@ -73,7 +73,7 @@ def test_deletes_nested_dir_with_files(self, tmp_path):
            td / "s" / "y",
            td / "s" / "z",
        ):
-            f.write_bytes(b"")

        try:
            rmtree(td)
@@ -95,7 +95,7 @@ def test_deletes_dir_with_readonly_files(self, tmp_path):
        for d in td, td / "sub":
            d.mkdir()
        for f in td / "x", td / "sub" / "y":
-            f.write_bytes(b"")
            f.chmod(0)

        try:
@@ -115,7 +115,7 @@ def test_avoids_changing_permissions_outside_tree(self, tmp_path):

        dir1 = tmp_path / "dir1"
        dir1.mkdir()
-        (dir1 / "file").write_bytes(b"")
        (dir1 / "file").chmod(stat.S_IRUSR)
        old_mode = (dir1 / "file").stat().st_mode

@@ -207,24 +207,28 @@ def _run_parse(name, value):
        )
        return ast.literal_eval(output)

    @pytest.mark.parametrize(
        "env_var_value, expected_truth_value",
        [
-            (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"),
        ],
    )
    @pytest.mark.parametrize(