new_contents: from praw.models import ModmailConversation
  
  from ... import UnitTest
  
  
  class TestModmailConversation(UnitTest):
      def test_parse(self):
          conversation = ModmailConversation(self.reddit,
                                             _data={'id': 'ik72'})
          assert str(conversation) == 'ik72'
  
subject: Test that ModmailConversation.id is preserved after fetch