          }
  
          serializer = AlbumSerializer(data=data)
          self.assertEqual(serializer.is_valid(), True)
          self.assertEqual(serializer.data, data)
  
      def test_nested_validation_error(self):
          """
          Incorrect nested serialization should return appropriate error data.
          """
 
</s> remove         serializer = AlbumSerializer(data=data)
 </s> add         serializer = self.AlbumSerializer(data=data) </s> remove class NestedSerializerTestCase(TestCase):
 </s> add  </s> remove         serializer = AlbumSerializer(data=data)
 </s> add         serializer = self.AlbumSerializer(data=data)
        self.assertEqual(serializer.object, data)
          }
  
          serializer = AlbumSerializer(data=data)
          self.assertEqual(serializer.is_valid(), True)
        self.assertEqual(serializer.object, data)
  
      def test_nested_validation_error(self):
          """
          Incorrect nested serialization should return appropriate error data.
          """
keep keep keep keep replace keep keep keep keep keep
 Extra tests for nested serializers 
rest_framework/tests/serializer_nested.py