[FIX] base: fix mock smtplib connection for server with 'starttls' encryption

During tests, when matching ir.mail_server has `smtp_encryption` set to
`starttls`, connect() will crash with an AttributeError as follows:

2022-09-22 07:04:27,882 20445 ERROR tests-150-starttls odoo.addons.base.tests.test_ir_mail_server: ERROR: TestIrMailServer.test_mail_server_send_email
Traceback (most recent call last):
  File "/home/odoo/src/odoo/15.0/odoo/tools/misc.py", line 804, in deco
    return func(*args, **kwargs)
  File "/home/odoo/src/odoo/15.0/odoo/addons/base/tests/test_ir_mail_server.py", line 261, in test_mail_server_send_email
    IrMailServer.send_email(message, mail_server_id=self.server_domain.id)
  File "/home/odoo/src/odoo/15.0/odoo/addons/base/models/ir_mail_server.py", line 575, in send_email
    smtp = self.connect(
  File "/usr/lib/python3.8/unittest/mock.py", line 1081, in __call__
    return self._mock_call(*args, **kwargs)
  File "/usr/lib/python3.8/unittest/mock.py", line 1085, in _mock_call
    return self._execute_mock_call(*args, **kwargs)
  File "/usr/lib/python3.8/unittest/mock.py", line 1146, in _execute_mock_call
    result = effect(*args, **kwargs)
  File "/home/odoo/src/odoo/15.0/odoo/addons/base/models/ir_mail_server.py", line 313, in connect
    connection.starttls(context=ssl_context)
AttributeError: 'TestingSMTPSession' object has no attribute 'starttls'

This commit adds a dummy `starttls()` method to `TestingSMTPSession` to
gracefully handle such case.

closes odoo/odoo#101962

X-original-commit: ec156901dd4db2fc7a2827b1eb78515f6259699e
Signed-off-by: Julien Castiaux <juc@odoo.com>
Signed-off-by: Xavier Alt (xal) <xal@odoo.com>

odoo/addons/base/tests/common.py

@@ -322,6 +322,9 @@ class MockSmtplibCase:
             def login(self, user, password):
                 pass
 
+            def starttls(self, keyfile=None, certfile=None, context=None):
+                pass
+
         self.testing_smtp_session = TestingSMTPSession()
 
         IrMailServer = self.env['ir.mail_server']

odoo/addons/base/tests/test_ir_mail_server.py

@@ -254,6 +254,20 @@ class TestIrMailServer(TransactionCase, MockSmtplibCase):
             from_filter='custom_domain.com',
         )
 
+        # Test when forcing the mail server and when smtp_encryption is "starttls"
+        self.server_domain.smtp_encryption = "starttls"
+        with self.mock_smtplib_connection():
+            message = self._build_email(mail_from='specific_user@test.com')
+            IrMailServer.send_email(message, mail_server_id=self.server_domain.id)
+
+        self.connect_mocked.assert_called_once()
+        self.assert_email_sent_smtp(
+            smtp_from='specific_user@test.com',
+            message_from='specific_user@test.com',
+            from_filter='test.com',
+        )
+
+
     @mute_logger('odoo.models.unlink')
     def test_mail_server_send_email_smtp_session(self):
         """Test all the cases when we provide the SMTP session.