[FIX] mail: set body on mail.message on event registration confirmation

Steps:
- Go to any event with tickets and using the ticket confirmation
template, sending 'after new confirmation'.
- Confirm a new attendee.
- An email is sent but the chatter only shows the attachment and the
subject, with no body.

Issue:
Chatter should show full content of the email.

Reason:
Above 16.2+ the 'body' is not implicitely set when genrating the
template in ``mail_template.send_mail()``. As discussed with RETH, when
requesting the 'body_html' for a template, setting the 'body' solves the
problem.

opw-3562438

closes odoo/odoo#151930

X-original-commit: 0a3d4b10a7c81d05d9bf6864b0b9a2f48f09b2a0
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/mail/models/mail_template.py

@@ -652,6 +652,8 @@ class MailTemplate(models.Model):
                 )
 
             values['body_html'] = self.env['mail.render.mixin']._replace_local_links(body)
+        if 'body_html' in values:
+            values['body'] = values['body_html']
 
         mail = self.env['mail.mail'].sudo().create(values)
 

addons/test_mail/tests/test_mail_template.py

@@ -105,6 +105,16 @@ class TestMailTemplate(TestMailTemplateCommon):
         self.assertFalse(mail.scheduled_date)
         self.assertEqual(mail.state, 'outgoing')
 
+    @mute_logger('odoo.addons.mail.models.mail_mail')
+    def test_template_send_mail_body(self):
+        """ Test that the body and body_html is set correctly in 'mail.mail'
+        when sending an email from mail.template """
+        mail_id = self.test_template.send_mail(self.test_record.id)
+        mail = self.env['mail.mail'].sudo().browse(mail_id)
+        body_result = '<p>EnglishBody for %s</p>' % self.test_record.name
+
+        self.assertEqual(mail.body_html, body_result)
+        self.assertEqual(mail.body, body_result)
 
 @tagged('mail_template', 'multi_lang')
 class TestMailTemplateLanguages(TestMailTemplateCommon):