[FIX] mass_mailing: send at least one a/b test if possible

When there is not enough recipients for the A/B testing percentage,
we pick a minimum of one recipients (if there is at least one) to
avoid sending a/b test to no one.

task-2713198

closes odoo/odoo#107488

X-original-commit: e1fa7b10250efc790452f02490ab84d2183698ff
Signed-off-by: Warnon Aurélien (awa) <awa@odoo.com>

addons/mass_mailing/models/mailing.py

@@ -261,8 +261,8 @@ class MassMailing(models.Model):
     def _compute_total(self):
         for mass_mailing in self:
             total = self.env[mass_mailing.mailing_model_real].search_count(mass_mailing._parse_mailing_domain())
-            if mass_mailing.ab_testing_pc < 100:
-                total = int(total / 100.0 * mass_mailing.ab_testing_pc)
+            if total and mass_mailing.ab_testing_pc < 100:
+                total = max(int(total / 100.0 * mass_mailing.ab_testing_pc), 1)
             mass_mailing.total = total
 
     def _compute_clicks_ratio(self):
@@ -990,7 +990,9 @@ class MassMailing(models.Model):
         # randomly choose a fragment
         if self.ab_testing_enabled and self.ab_testing_pc < 100:
             contact_nbr = self.env[self.mailing_model_real].search_count(mailing_domain)
-            topick = int(contact_nbr / 100.0 * self.ab_testing_pc)
+            topick = 0
+            if contact_nbr:
+                topick = max(int(contact_nbr / 100.0 * self.ab_testing_pc), 1)
             if self.campaign_id and self.ab_testing_enabled:
                 already_mailed = self.campaign_id._get_mailing_recipients()[self.campaign_id.id]
             else:

addons/mass_mailing/tests/test_mailing_ab_testing.py

@@ -173,3 +173,22 @@ class TestMailingABTesting(MassMailCommon):
         self.ab_testing_mailing_ids.invalidate_recordset()
         winner_mailing = self.ab_testing_campaign.mailing_mail_ids.filtered(lambda mailing: mailing.ab_testing_pc == 100)
         self.assertEqual(winner_mailing.subject, 'A/B Testing V2')
+
+    @mute_logger('odoo.addons.mail.models.mail_mail')
+    @users('user_marketing')
+    def test_mailing_ab_testing_minimum_participants(self):
+        """ Test that it should send minimum one mail(if possible) when ab_testing_pc is too small compared to the amount of targeted records."""
+        mailing_list = self._create_mailing_list_of_x_contacts(10)
+        ab_testing = self.env['mailing.mailing'].create({
+            'subject': 'A/B Testing SMS V1',
+            'contact_list_ids': mailing_list.ids,
+            'ab_testing_enabled': True,
+            'ab_testing_pc': 2,
+            'ab_testing_schedule_datetime': datetime.now(),
+            'mailing_type': 'mail',
+            'campaign_id': self.ab_testing_campaign.id,
+        })
+        with self.mock_mail_gateway():
+            ab_testing.action_send_mail()
+        self.assertEqual(ab_testing.state, 'done')
+        self.assertEqual(len(self._mails), 1)