text: from django.core.exceptions import ValidationError
  from tests.core.test_cases import BookCenterTestCase
  
  
  class BlogPostAuthorModelTests(BookCenterTestCase):
  
      def test_blog_post_author_model_when_first_name_contains_non_english_chars__expect_exception(self):
          self.blog_post_author.first_name = 'Бълхичкo'
  
          with self.assertRaises(ValidationError) as context:
              self.blog_post_author.full_clean()
              self.blog_post_author.save()
  
          self.assertIsNotNone(context.exception)
  
      def test_blog_post_author_model_when_last_name_contains_non_english_chars__expect_exception(self):
          self.blog_post_author.last_name = 'Хлебарков'
  
          with self.assertRaises(ValidationError) as context:
              self.blog_post_author.full_clean()
              self.blog_post_author.save()
          self.assertIsNotNone(context.exception)