new_contents: from sqlalchemy.exc import StatementError
  from project.models import MailTemplate
  from project.tests.utils import ProjectTestCase
  
  
  class TestMailTemplateBl(ProjectTestCase):
  
      def test_get(self):
          mail1 = MailTemplate.bl.get(MailTemplate.MAIL.CV)
          mail2 = MailTemplate.query.filter(
              MailTemplate.mail == MailTemplate.MAIL.CV
          ).one()
          self.assertEqual(mail1, mail2)
  
          with self.assertRaises(StatementError):
              MailTemplate.bl.get(100)
  
subject: add tests