[IMP] mail: improve 'real author' detection when posting a message

When posting a message, author is added in followers in order to receive
answers. They also do not receive its own messages, to avoid being notified
of something they just posted.

However the real author is not always the message author. In this commit
we better define this author
  * when current user is active, real author is the current user. It means
    posting on behalf of someone will send answers to you, not to the
    spoofed partner;
  * when current user is inactive, real author is the message author. An
    inactive current user means the post was probably done as sudo, aka
    in the mailgateway or frontend. In that case we don't want to add
    odoobot in followers, but the actual message author;

Task-3093257 (Mail: The Composer Update)

Part-of: odoo/odoo#107356

addons/mail/models/mail_thread.py

@@ -1927,9 +1927,25 @@ class MailThread(models.AbstractModel):
         )  # attachement_ids, body
         new_message = self._message_create([msg_values])
 
-        if msg_values['author_id'] and msg_values['message_type'] != 'notification' and not self._context.get('mail_create_nosubscribe'):
-            if self.env['res.partner'].browse(msg_values['author_id']).active:  # we dont want to add odoobot/inactive as a follower
-                self._message_subscribe(partner_ids=[msg_values['author_id']])
+        # subscribe author(s) so that they receive answers; do it only when it is
+        # a manual post by the author (aka not a system notification, not a message
+        # posted 'in behalf of', and if still active).
+        author_subscribe = (not self._context.get('mail_create_nosubscribe') and
+                             msg_values['message_type'] != 'notification')
+        if author_subscribe:
+            real_author_id = False
+            # if current user is active, they are the one doing the action and should
+            # be notified of answers. If they are inactive they are posting on behalf
+            # of someone else (a custom, mailgateway, ...) and the real author is the
+            # message author
+            if self.env.user.active:
+                real_author_id = self.env.user.partner_id.id
+            elif msg_values['author_id']:
+                author = self.env['res.partner'].browse(msg_values['author_id'])
+                if author.active:
+                    real_author_id = author.id
+            if real_author_id:
+                self._message_subscribe(partner_ids=[real_author_id])
 
         self._message_post_after_hook(new_message, msg_values)
         self._notify_thread(new_message, msg_values, **notif_kwargs)
@@ -3220,9 +3236,17 @@ class MailThread(models.AbstractModel):
 
         # notify author of its own messages, False by default
         notify_author = kwargs.get('notify_author') or self.env.context.get('mail_notify_author')
-        author_id = msg_vals.get('author_id') or message.author_id.id
+        real_author_id = False
+        if not notify_author:
+            if self.env.user.active:
+                real_author_id = self.env.user.partner_id.id
+            elif msg_vals.get('author_id'):
+                real_author_id = msg_vals['author_id']
+            else:
+                real_author_id = message.author_id.id
+
         for pid, pdata in res.items():
-            if pid and not notify_author and pid == author_id:
+            if pid and pid == real_author_id:
                 continue
             if pdata['active'] is False:
                 continue

addons/test_mail/tests/test_message_post.py

@@ -659,6 +659,61 @@ class TestMessagePost(TestMessagePostCommon, CronMixinCase):
                 partner_ids=self.partner_portal.ids,
             )
 
+    @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink')
+    @users('employee')
+    def test_message_post_author(self):
+        """ Test author recognition """
+        test_record = self.test_record.with_env(self.env)
+
+        # when a user spoofs the author: the actual author is the current user
+        # and not the message author
+        with self.assertSinglePostNotifications(
+                [{'partner': self.partner_admin, 'type': 'email'}],
+                {'content': 'Body'}
+            ):
+            new_message = test_record.message_post(
+                author_id=self.partner_employee_2.id,
+                body='Body',
+                message_type='comment',
+                subtype_xmlid='mail.mt_comment',
+                partner_ids=[self.partner_admin.id],
+            )
+
+        self.assertMessageFields(
+            new_message,
+            {'author_id': self.partner_employee_2,
+             'email_from': formataddr((self.partner_employee_2.name, self.partner_employee_2.email_normalized)),
+             'message_type': 'comment',
+             'notified_partner_ids': self.partner_admin,
+             'subtype_id': self.env.ref('mail.mt_comment'),
+            }
+        )
+        self.assertEqual(test_record.message_partner_ids, self.partner_employee,
+                         'Real author is added in followers, not message author')
+
+        # should be skipped with notifications
+        test_record.message_unsubscribe(partner_ids=self.partner_employee.ids)
+        _new_message = test_record.message_post(
+            author_id=self.partner_employee_2.id,
+            body='Body',
+            message_type='notification',
+            subtype_xmlid='mail.mt_comment',
+            partner_ids=[self.partner_admin.id],
+        )
+        self.assertFalse(test_record.message_partner_ids, 'Notification should not add author in followers')
+
+        # inactive users are not considered as authors
+        self.env.user.with_user(self.user_admin).active = False
+        _new_message = test_record.message_post(
+            author_id=self.partner_employee_2.id,
+            body='Body',
+            message_type='comment',
+            subtype_xmlid='mail.mt_comment',
+            partner_ids=[self.partner_admin.id],
+        )
+        self.assertEqual(test_record.message_partner_ids, self.partner_employee_2,
+                         'Author is the message author when user is inactive, and shoud be added in followers')
+
     @mute_logger('odoo.addons.mail.models.mail_mail', 'odoo.models.unlink', 'odoo.tests')
     @users('employee')
     def test_message_post_defaults(self):

addons/website_blog/tests/test_website_blog_flow.py

@@ -56,7 +56,7 @@ class TestWebsiteBlogFlow(TestWebsiteBlogCommon):
             'website_blog: peuple following a blog should be notified of a published post')
 
         # Armand posts a message -> becomes follower
-        self.test_blog_post.sudo().message_post(
+        self.test_blog_post.with_user(self.user_employee).message_post(
             body='Armande BlogUser Commented',
             message_type='comment',
             author_id=self.user_employee.partner_id.id,