text: from testing.testcases import TestCase
  
  class CommentModelTests(TestCase):
  
      def setUp(self):
          self.clear_cache()
          self.linghu = self.create_user('linghu')
          self.tweet = self.create_tweet(self.linghu)
          self.comment = self.create_comment(self.linghu, self.tweet)
  
      def test_comment(self):
          self.assertNotEqual(self.comment.__str__(), None)
  
      def test_like_set(self):
          self.create_like(self.linghu, self.comment)
          self.assertEqual(self.comment.like_set.count(), 1)
  
          self.create_like(self.linghu, self.comment)
          self.assertEqual(self.comment.like_set.count(), 1)
  
          dongxie = self.create_user('dongxie')
          self.create_like(dongxie, self.comment)
          self.assertEqual(self.comment.like_set.count(), 2)
  