embedded bots: Log warning when bot quit()s.

External bots may call bot_handler.quit() when
they wish to terminate, e.g. due to a misconfiguration.
Currently, embedded bots ignore calls to quit(), even
though they signal a problem. This commit does the first
step in handling quit() calls by logging a warning.

zerver/lib/bot_lib.py

@@ -57,6 +57,9 @@ class StateHandler:
     def contains(self, key: Text) -> bool:
         return is_key_in_bot_storage(self.user_profile, key)
 
+class EmbeddedBotQuitException(Exception):
+    pass
+
 class EmbeddedBotHandler:
     def __init__(self, user_profile: UserProfile) -> None:
         # Only expose a subset of our UserProfile's functionality
@@ -113,3 +116,6 @@ class EmbeddedBotHandler:
             if optional:
                 return dict()
             raise
+
+    def quit(self, message: str= "") -> None:
+        raise EmbeddedBotQuitException(message)

zerver/tests/test_embedded_bot_system.py

@@ -1,8 +1,10 @@
 # -*- coding: utf-8 -*-
 
 from unittest import mock
+from mock import patch
 from typing import Any, Dict, Tuple, Text, Optional
 
+from zerver.lib.bot_lib import EmbeddedBotQuitException
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.models import UserProfile, Recipient, get_display_recipient
 
@@ -47,6 +49,15 @@ class TestEmbeddedBotMessaging(ZulipTestCase):
         last_message = self.get_last_message()
         self.assertEqual(last_message.content, "foo")
 
+    def test_embedded_bot_quit_exception(self) -> None:
+        with patch('zulip_bots.bots.helloworld.helloworld.HelloWorldHandler.handle_message',
+                   side_effect=EmbeddedBotQuitException("I'm quitting!")):
+            with patch('logging.warning') as mock_logging:
+                self.send_stream_message(self.user_profile.email, "Denmark",
+                                         content="@**{}** foo".format(self.bot_profile.full_name),
+                                         topic_name="bar")
+                mock_logging.assert_called_once_with("I'm quitting!")
+
 class TestEmbeddedBotFailures(ZulipTestCase):
     @mock.patch("logging.error")
     def test_invalid_embedded_bot_service(self, logging_error_mock: mock.Mock) -> None:

zerver/worker/queue_processors.py

@@ -43,7 +43,7 @@ from zerver.lib.outgoing_webhook import do_rest_call, get_outgoing_webhook_servi
 from zerver.models import get_bot_services
 from zulip import Client
 from zulip_bots.lib import extract_query_without_mention
-from zerver.lib.bot_lib import EmbeddedBotHandler, get_bot_handler
+from zerver.lib.bot_lib import EmbeddedBotHandler, get_bot_handler, EmbeddedBotQuitException
 
 import os
 import sys
@@ -529,19 +529,22 @@ class EmbeddedBotWorker(QueueProcessingWorker):
                 logging.error("Error: User %s has bot with invalid embedded bot service %s" % (
                     user_profile_id, service.name))
                 continue
-            if hasattr(bot_handler, 'initialize'):
-                bot_handler.initialize(self.get_bot_api_client(user_profile))
-            if event['trigger'] == 'mention':
-                message['content'] = extract_query_without_mention(
+            try:
+                if hasattr(bot_handler, 'initialize'):
+                        bot_handler.initialize(self.get_bot_api_client(user_profile))
+                if event['trigger'] == 'mention':
+                    message['content'] = extract_query_without_mention(
+                        message=message,
+                        client=self.get_bot_api_client(user_profile),
+                    )
+                    if message['content'] is None:
+                        return
+                bot_handler.handle_message(
                     message=message,
-                    client=self.get_bot_api_client(user_profile),
+                    bot_handler=self.get_bot_api_client(user_profile)
                 )
-                if message['content'] is None:
-                    return
-            bot_handler.handle_message(
-                message=message,
-                bot_handler=self.get_bot_api_client(user_profile)
-            )
+            except EmbeddedBotQuitException as e:
+                logging.warning(str(e))
 
 @assign_queue('deferred_work')
 class DeferredWorker(QueueProcessingWorker):