def test_none_or_empty(self):
     ct = get_sort_order_from_string(None)
     self.assertIsNone(ct)
     ct = get_sort_order_from_string('')
     self.assertIsNone(ct)
 def test_descending(self):
     ct = get_sort_order_from_string('descending')
     self.assertEqual(ct, SortOrder.DESCENDING)
 def test_invalid(self):
     with self.assertRaises(InvalidArgument):
         get_sort_order_from_string('foo')