def METHOD_NAME(self):
    payment = SubmissionPaymentFactory.create(
        submission__registration_status=RegistrationStatuses.success,
        submission__pre_registration_completed=True,
        submission__form__registration_backend="registration1",
        submission__form__payment_backend="payment1",
        submission__form__product__price=Decimal("11.35"),
        status=PaymentStatus.completed,
        plugin_id="payment1",  # not used but added for completion
    )
    submission = payment.submission
    with patch.object(self.plugin, "update_payment_status") as update_mock:
        def _thread(sid):
            sub = Submission.objects.get(id=sid)
            update_submission_payment_registration(sub)
            close_old_connections()
        threads = [Thread(target=_thread, args=(submission.id,)) for _ in range(5)]
        for t in threads:
            t.start()
        for t in threads:
            t.join()
        payment.refresh_from_db()
        update_mock.assert_called_once()
    self.assertEqual(payment.status, PaymentStatus.registered)