new_contents: from django.apps import apps
  from django.contrib import admin
  from django.contrib.admin.checks import check_admin_app
  from django.db import models
  from django.test import TestCase
  
  from localized_fields.fields import LocalizedField
  from localized_fields.admin import LocalizedFieldsAdminMixin
  
  from tests.fake_model import get_fake_model
  
  
  class LocalizedFieldsAdminMixinTestCase(TestCase):
      """Tests the :see:LocalizedFieldsAdminMixin class."""
  
      TestModel = None
      TestRelModel = None
  
      @classmethod
      def setUpClass(cls):
          """Creates the test model in the database."""
  
          super(LocalizedFieldsAdminMixinTestCase, cls).setUpClass()
  
          cls.TestRelModel = get_fake_model(
              {
                  'description': LocalizedField()
              }
          )
          cls.TestModel = get_fake_model(
              {
                  'title': LocalizedField(),
                  'rel': models.ForeignKey(cls.TestRelModel,
                                           on_delete=models.CASCADE)
              }
          )
  
      def tearDown(self):
          if admin.site.is_registered(self.TestModel):
              admin.site.unregister(self.TestModel)
          if admin.site.is_registered(self.TestRelModel):
              admin.site.unregister(self.TestRelModel)
  
      @classmethod
      def test_model_admin(cls):
          """Tests whether :see:LocalizedFieldsAdminMixin
          mixin are works with admin.ModelAdmin"""
  
          @admin.register(cls.TestModel)
          class TestModelAdmin(LocalizedFieldsAdminMixin, admin.ModelAdmin):
              pass
  
          assert len(check_admin_app(apps.get_app_configs())) == 0
  
      @classmethod
      def test_stackedmodel_admin(cls):
          """Tests whether :see:LocalizedFieldsAdminMixin mixin are works
          with admin.StackedInline"""
  
          class TestModelStackedInline(LocalizedFieldsAdminMixin,
                                       admin.StackedInline):
              model = cls.TestModel
  
          @admin.register(cls.TestRelModel)
          class TestRelModelAdmin(admin.ModelAdmin):
              inlines = [
                  TestModelStackedInline,
              ]
  
          assert len(check_admin_app(apps.get_app_configs())) == 0
  
      @classmethod
      def test_tabularmodel_admin(cls):
          """Tests whether :see:LocalizedFieldsAdminMixin mixin are works
          with admin.TabularInline"""
  
          class TestModelTabularInline(LocalizedFieldsAdminMixin,
                                       admin.TabularInline):
              model = cls.TestModel
  
          @admin.register(cls.TestRelModel)
          class TestRelModelAdmin(admin.ModelAdmin):
              inlines = [
                  TestModelTabularInline,
              ]
  
          assert len(check_admin_app(apps.get_app_configs())) == 0
  
subject: Add tests for LocalizedFieldsAdminMixin