new_contents: from unittest import TestCase
  
  from ..models import Artist, Hyperlink
  from ..serializers import ArtistSerializer, HyperlinkSerializer
  
  
  class HyperlinkSerializerTest(TestCase):
  
      """Tests for Hyperlink serializer."""
  
      def test_valid_fields(self):
          id_ = 4
          name = 'jamendo'
          display_name = "Jamendo"
          url = "http://www.jamendo.com/artist/1333"
          link = Hyperlink(id=id_, name=name, url=url)
          serializer = HyperlinkSerializer(link)
          self.assertEqual(serializer.data, {
              'id': id_,
              'name': name,
              'display_name': display_name,
              'url': url,
          })
  
  
  class ArtistSerializerTest(TestCase):
  
      """Tests for Artist serializer."""
  
      def test_no_links(self):
          id_ = 2
          name = "Brad Sucks"
          artist = Artist(id=id_, name=name)
          serializer = ArtistSerializer(artist)
          self.assertEqual(serializer.data, {
              'id': id_,
              'name': name,
              'links': [],
          })
  
subject: Add tests for artist serializers