              ],
              'url_field': [
                  ('max_length', 1024),
              ],
          }
  
      def field_test(self, field):
          serializer = self.serializer_class(data={})
          self.assertEqual(serializer.is_valid(), True)
 
</s>
            'nullable_char_field': [
                ('max_length', 1024),
                ('allow_none', True),
            ],
              ],
              'url_field': [
                  ('max_length', 1024),
              ],
            'nullable_char_field': [
                ('max_length', 1024),
                ('allow_none', True),
            ],
          }
  
      def field_test(self, field):
          serializer = self.serializer_class(data={})
          self.assertEqual(serializer.is_valid(), True)
keep keep keep add keep keep keep keep keep
 Test for setting allow_none=True for nullable CharFields
rest_framework/tests/test_serializer.py