def METHOD_NAME(self):
    old_service = ServiceFactory(name='test')
    new_service = ServiceFactory(name='prod')
    old_service.business_owners.add(UserFactory(email='test1@test.pl'))
    new_service.business_owners.add(UserFactory(email='test2@test.pl'))
    old_service_env = ServiceEnvironmentFactory(service=old_service)
    new_service_env = ServiceEnvironmentFactory(service=new_service)
    # update without triggering signals
    DataCenterAsset.objects.filter(
        pk=self.dca.pk
    ).update(service_env=old_service_env)
    data_custom_fields = {
        'TOTAL_FORMS': 3,
        'INITIAL_FORMS': 0,
    }
    self._update_dca(
        dca_data={'service_env': new_service_env.id},
        inline_data=data_custom_fields
    )
    self.dca.refresh_from_db()
    self.assertEqual(len(mail.outbox), 1)
    self.assertEqual(
        'Device has been assigned to Service: {} ({})'.format(
            new_service, self.dca
        ),
        mail.outbox[0].subject
    )
    self.assertCountEqual(
        mail.outbox[0].to,
        ['test1@test.pl', 'test2@test.pl']
    )