[REF] test_mass_mailing: use odoo test helper method to create test users

Purpose of this commit is to use the newly introduced helper to create
test users in a quick way and reduce code duplication.

This commit is linked to task ID 1889703 and PR #27526.

addons/test_mass_mailing/tests/common.py

@@ -2,6 +2,7 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 from odoo.addons.test_mail.tests import common
+from odoo.addons.test_mail.tests.common import mail_new_test_user
 from odoo.tests import tagged
 
 
@@ -17,14 +18,7 @@ class MassMailingCase(common.MockEmails, common.BaseFunctionalTest):
             'login': 'emp',
         })
 
-        cls.user_marketing = cls.env['res.users'].with_context(cls._create_context('res.users')).create({
-            'name': 'Ernest Employee',
-            'login': 'marketing',
-            'email': 'e.e@example.com',
-            'signature': '--\nErnest',
-            'notification_type': 'email',
-            'groups_id': [
-                (6, 0, [cls.env.ref('base.group_user').id]),
-                (6, 0, [cls.env.ref('mass_mailing.group_mass_mailing_user').id])
-            ],
-        })
+        cls.user_marketing = mail_new_test_user(
+            cls.env, login='marketing',
+            groups='base.group_user,mass_mailing.group_mass_mailing_user',
+            name='Martial Marketing', signature='--\nMartial')