text: # -*- coding: utf-8 -*-
  from django.core.exceptions import ImproperlyConfigured
  from django.test.testcases import TestCase
  from filer.fields.image import FilerImageField
  
  class FieldsTests(TestCase):
      def test_related_name_validation(self):
          self.assertRaises(ImproperlyConfigured, FilerImageField, related_name='thumbnails')
          FilerImageField(related_name='not_thumbnails')
  