new_contents: # Licensed under a 3-clause BSD style license - see LICENSE.rst
  # -*- coding: utf-8 -*-
  
  import pytest
  
  from asdf.tests.helpers import assert_roundtrip_tree
  
  from astropy.time import Time
  
  
  @pytest.mark.parametrize('fmt', Time.FORMATS.keys())
  def test_timedelta(fmt, tmpdir):
  
      t1 = Time(Time.now(), format=fmt)
      t2 = Time(Time.now(), format=fmt)
  
      td = t2 - t1
      tree = dict(timedelta=td)
      assert_roundtrip_tree(tree, tmpdir)
  
subject: Add test for serializing TimeDelta using ASDF