          self.field_test('url_field')
  
  
  class MetadataSerializer(serializers.Serializer):
      field1 = serializers.CharField(3, required=True)
      field2 = serializers.CharField(10, required=False)
  
  
  class MetadataSerializerTestCase(TestCase):
      def setUp(self):
          self.serializer = MetadataSerializer()
 
</s> remove     #_hyperlink_field_class = HyperlinkedRelatedField
    #_hyperlink_identify_field_class = HyperlinkedIdentityField
 </s> add     # _hyperlink_field_class = HyperlinkedRelatedField
    # _hyperlink_identify_field_class = HyperlinkedIdentityField </s> remove         super(CharField, self).__init__(*args, **kwargs)
 </s> add         self.max_length = kwargs.pop('max_length', None)
        self.min_length = kwargs.pop('min_length', None)
        super(CharField, self).__init__(**kwargs) </s> remove                 files = None
 </s> add                 # files = None </s> remove                 files = request.FILES
 </s> add                 # files = request.FILES </s> remove             files = None
 </s> add             # files = None
    field1 = serializers.CharField(max_length=3, required=True)
    field2 = serializers.CharField(max_length=10, required=False)
          self.field_test('url_field')
  
  
  class MetadataSerializer(serializers.Serializer):
    field1 = serializers.CharField(max_length=3, required=True)
    field2 = serializers.CharField(max_length=10, required=False)
    field1 = serializers.CharField(max_length=3, required=True)
    field2 = serializers.CharField(max_length=10, required=False)
  
  
  class MetadataSerializerTestCase(TestCase):
      def setUp(self):
          self.serializer = MetadataSerializer()
keep keep keep keep replace replace keep keep keep keep keep
 Add relations and get tests running 
tests/test_serializer.py