new_contents: from django.test import TestCase
  
  from django_backend.backend.base.backends import ModelBackend
  from django_backend.sitebackend import SiteBackend
  
  from .models import OneFieldModel
  
  
  class ModelBackendTest(TestCase):
      def setUp(self):
          self.site = SiteBackend(id='test')
  
      def get_basic_backend(self, **kwargs):
          defaults = {
              'id': 'onefieldmodel',
              'model': OneFieldModel,
          }
          defaults.update(**kwargs)
          return self.site.register(ModelBackend, **defaults)
  
      def test_registration(self):
          self.site.register(
              ModelBackend,
              id='onefieldmodel',
              model=OneFieldModel)
  
      def test_get_form_class(self):
          backend = self.get_basic_backend()
          form_class = backend.get_form_class()
  
          self.assertEqual(form_class.Meta.model, OneFieldModel)
          self.assertEqual(form_class.base_fields.keys(), ['name'])
  
subject: Add basic tests for ModelBackend