def METHOD_NAME(self) -> None:
    with TempSubvolumes(Path(sys.argv[0])) as ts:
        sv = ts.create("root")
        sv.run_as_root(["mkdir", sv.path("/etc")]).check_returncode()
        sv.overwrite_path_as_root(GROUP_FILE_PATH, _SAMPLE_ETC_GROUP)
        GroupItem(from_target="t", name="foo").build(sv)
        GroupItem(from_target="t", name="bar").build(sv)
        self.assertEqual(
            augment_group_file(
                augment_group_file(_SAMPLE_ETC_GROUP, "foo", 1000),
                "bar",
                1001,
            ),
            sv.path("/etc/group").read_text(),
        )