'Yields the name of a valid tar file of size n_bytes.'

@contextlib.contextmanager
def dummy_tar_file(self, n_bytes):

    with tempfile.NamedTemporaryFile(delete=False) as tar_file:
        self.write_dummy_tar_content(n_bytes, tar_file)
        tar_file.seek(0)
        (yield tar_file.name)
