def METHOD_NAME(self, filename):
    """Copies a backup of a test data file to the temp dir and sets its
    mode to writeable.
    """
    shutil.copy(
        os.path.expanduser(self.data(filename)),
        os.path.expanduser(self.temp(filename)),
    )
    os.chmod(os.path.expanduser(self.temp(filename)), stat.S_IREAD | stat.S_IWRITE)