[FIX] event_sale : compute attendees on cancel SO

Steps to reproduce:

- create a sale order with an event registration,
- on the event, the number of attendees is well computed
- cancel the sale order
- on the event, the number of attendees is still the same as before

Cause of the issue

There was no specific action for canceling a sale order linked
to an event registration

Solution

Add a action_cancel method which cancel also the sale order lines when
canceling the sale order

Also add a test to ensure the flow will not break in the future

opw-2576790

closes odoo/odoo#74481

Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/event_sale/models/sale_order.py

@@ -23,10 +23,14 @@ class SaleOrder(models.Model):
                     .with_context(default_sale_order_id=so.id) \
                     .for_xml_id('event_sale', 'action_sale_order_event_registration')
         return res
+    
+    def action_cancel(self):
+        self.mapped('order_line')._cancel_associated_registrations()
+        return super(SaleOrder, self).action_cancel()
 
     def unlink(self):
         self.mapped('order_line')._unlink_associated_registrations()
-        super(SaleOrder, self).unlink()
+        return super(SaleOrder, self).unlink()
 
 
 class SaleOrderLine(models.Model):
@@ -91,6 +95,9 @@ class SaleOrderLine(models.Model):
         self._unlink_associated_registrations()
         super(SaleOrderLine, self).unlink()
 
+    def _cancel_associated_registrations(self):
+        self.env['event.registration'].search([('sale_order_line_id', 'in', self.ids)]).button_reg_cancel()
+
     def _unlink_associated_registrations(self):
         self.env['event.registration'].search([('sale_order_line_id', 'in', self.ids)]).unlink()
 

addons/event_sale/tests/test_event_sale.py

@@ -145,3 +145,13 @@ class EventSaleTest(TransactionCase):
         self.assertEqual(event.seats_expected, 1)
         self.sale_order.order_line.unlink()
         self.assertEqual(event.seats_expected, 0)
+        
+    @users('user_salesman')
+    def test_cancel_so(self):
+        """ This test ensures that when canceling a sale order, if the latter is linked to an event registration,
+        the number of expected seats will be correctly updated """
+        event = self.env['event.event'].browse(self.event.ids)
+        self.register_person.action_make_registration()
+        self.assertEqual(event.seats_expected, 1)
+        self.sale_order.action_cancel()
+        self.assertEqual(event.seats_expected, 0)