[FIX] mass_mailing: duplicate the "Send final on" field when copy

Before this commit:
In the `mailings` when we enable the A/B testing and click on the "Create an Alternative" button,
the "Send final on" field doesn't copy to the new mailing.

Reason:
The related field are copy `false` by default.

After this Commit:
Now it will copy the "Send final on" into a new mailing

closes odoo/odoo#138195

Task: 3465887
X-original-commit: 3d6dd2402a65af40c77692250fd710d3355960e7
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/mass_mailing/models/mailing.py

@@ -539,6 +539,8 @@ class MassMailing(models.Model):
         default = dict(default or {}, contact_list_ids=self.contact_list_ids.ids)
         if self.mail_server_id and not self.mail_server_id.active:
             default['mail_server_id'] = self._get_default_mail_server_id()
+        if self.ab_testing_enabled:
+            default['ab_testing_schedule_datetime'] = self.ab_testing_schedule_datetime
         return super(MassMailing, self).copy(default=default)
 
     def _group_expand_states(self, states, domain, order):

addons/mass_mailing/tests/test_mailing_ab_testing.py

@@ -6,6 +6,8 @@ from datetime import datetime, timedelta
 from odoo.addons.mass_mailing.tests.common import MassMailCommon
 from odoo.tests import users, tagged
 from odoo.tools import mute_logger
+from odoo.tests.common import Form
+from odoo import fields
 
 
 @tagged('post_install', '-at_install')
@@ -192,3 +194,11 @@ class TestMailingABTesting(MassMailCommon):
             ab_testing.action_send_mail()
         self.assertEqual(ab_testing.state, 'done')
         self.assertEqual(len(self._mails), 1)
+
+    def test_mailing_ab_testing_duplicate_date(self):
+        """ Test that "Send final on" date value should be copied in new mass_mailing """
+        ab_testing_mail_1 = Form(self.ab_testing_mailing_1)
+        ab_testing_mail_1.ab_testing_schedule_datetime = datetime.now() + timedelta(days=10)
+        action = ab_testing_mail_1.save().action_duplicate()
+        ab_testing_mailing_2 = self.env[action['res_model']].browse(action['res_id'])
+        self.assertEqual(fields.Datetime.to_string(ab_testing_mailing_2.ab_testing_schedule_datetime), ab_testing_mail_1.ab_testing_schedule_datetime)