new_contents: from django.test import TestCase
  from django.core.exceptions import ValidationError
  
  from master_data.models import Nationality
  
  
  class NationalityModeTestCases(TestCase):
      def setUp(self):
          self.nationality, created = Nationality(name='Egyptian')
  
      def test_create_new_nationality(self):
          new_nationality = Nationality(name='American')
          new_nationality.save()
  
          self.assertTrue(new_nationality.pk)
          self.assertTrue(new_nationality.is_active)
          self.assertIsInstance(new_nationality, Nationality)
  
      def test_update_nationality(self):
          self.nationality.name = 'Egypt'
          self.nationality.save()
  
          self.assertTrue(self.nationality.pk)
          self.assertNotEqual('Egyptian', self.nationality.name)
  
      def test_delete_nationality(self):
          self.nationality.delete()
  
          self.assertFalse(self.nationality.pk)
  
      def test_add_new_nationality_with_duplicate_name(self):
          new_nationality = Nationality(name=self.nationality.name)
  
          with self.assertRaises(ValidationError):
              new_nationality.save()
  
      def test_deactivate_nationality(self):
          self.nationality.is_active = False
          self.nationality.save()
  
          self.assertFalse(self.nationality.is_active)
  
subject: Add test for nationality model