fix old subscribers group attribution

Si un utilisateur faisait sa première cotisation alors qu'il avait déjà un compte AE (par exemple, en effectuant un achat sur l'eboutic avant sa cotisation), alors il pouvait se retrouver hors du groupe Anciens cotisants.

subscription/tests/test_new_subscription.py

@@ -5,6 +5,7 @@ from typing import Callable
 
 import pytest
 from dateutil.relativedelta import relativedelta
+from django.conf import settings
 from django.contrib.auth.models import Permission
 from django.test import Client
 from django.urls import reverse
@@ -14,8 +15,10 @@ from pytest_django.asserts import assertRedirects
 from pytest_django.fixtures import SettingsWrapper
 
 from core.baker_recipes import board_user, old_subscriber_user, subscriber_user
-from core.models import User
+from core.models import Group, User
+from counter.models import Customer
 from subscription.forms import SubscriptionExistingUserForm, SubscriptionNewUserForm
+from subscription.models import Subscription
 
 
 @pytest.mark.django_db
@@ -189,3 +192,17 @@ def test_submit_form_new_user(client: Client, settings: SettingsWrapper):
             kwargs={"subscription_id": current_subscription.id},
         ),
     )
+
+
+@pytest.mark.django_db
+def test_subscription_for_user_that_had_a_sith_account():
+    """Test that a newly subscribed user is added to the old subscribers group,
+    even if there already was a sith account (e.g. created during an eboutic purchase).
+    """
+    user = baker.make(User)
+    Customer.get_or_create(user)
+    group = Group.objects.get(id=settings.SITH_GROUP_OLD_SUBSCRIBERS_ID)
+    assert not user.groups.contains(group)
+    subscription = baker.prepare(Subscription, member=user)
+    subscription.save()
+    assert user.groups.contains(group)