Add basic test for FeedbackBot.

This sets up a new test class with a simple
test, mostly for increasing coverage. The class
should in the future be extended to properly
verify the handle_feedback() logic.

zerver/lib/actions.py

@@ -1277,7 +1277,6 @@ def do_send_messages(messages_maybe_none: Sequence[Optional[MutableMapping[str,
                 queue_json_publish(
                     'feedback_messages',
                     wide_message_dict,
-                    lambda x: None
                 )
 
         if message['message'].recipient.type == Recipient.PERSONAL:

zerver/tests/test_feedback.py

@@ -0,0 +1,12 @@
+from unittest.mock import patch, MagicMock
+from django.conf import settings
+from zerver.lib.test_classes import ZulipTestCase
+
+class TestFeedbackBot(ZulipTestCase):
+    @patch('logging.info')
+    def test_pm_to_feedback_bot(self, logging_info_mock: MagicMock) -> None:
+        with self.settings(ENABLE_FEEDBACK=True):
+            user_email = self.example_email("othello")
+            self.send_personal_message(user_email, settings.FEEDBACK_BOT,
+                                       content="I am a feedback message.")
+            logging_info_mock.assert_called_once_with("Received feedback from {}".format(user_email))