queue_processors: Add error coverage for MessageSenderWorker.

zerver/tests/test_tornado.py

@@ -37,6 +37,7 @@ from zerver.tornado.views import get_events_backend
 from http.cookies import SimpleCookie
 import urllib.parse
 
+from unittest.mock import patch
 from typing import Any, Callable, Dict, Generator, Optional, Text, List, cast
 
 class TornadoWebTestCase(AsyncHTTPTestCase, ZulipTestCase):
@@ -407,3 +408,52 @@ class TornadoTestCase(WebSocketBaseTestCase):
         msg_resp = yield ws.read_message()
         self._check_message_sending(request_id, ack_resp, msg_resp, user_profile, queue_events_data)
         yield self.close(ws)
+
+    @gen_test
+    def test_sending_message_error(self) -> Any:
+        user_profile = self.example_user('hamlet')
+        cookies = self._get_cookies(user_profile)
+        cookie_header = self.get_cookie_header(cookies)
+        queue_events_data = self._get_queue_events_data(user_profile.email)
+        ws = yield self.ws_connect('/sockjs/366/v8nw22qe/websocket', cookie_header=cookie_header)
+        yield ws.read_message()
+        yield self._websocket_auth(ws, queue_events_data, cookies)
+        request_id = ':'.join((queue_events_data['response']['queue_id'], '1'))
+        user_message = {
+            "req_id": request_id,
+            "type": "request",
+            "request": {
+                "client": "website",
+                "type": "stream",
+                "subject": "Stream message",
+                "stream": "Denmark",
+                "private_message_recipient": "",
+                "content": "hello",
+                "sender_id": user_profile.id,
+                "queue_id": queue_events_data['response']['queue_id'],
+                "to": ujson.dumps(["Denmark"]),
+                "reply_to": self.example_email('hamlet'),
+                "local_id": -1
+            }
+        }
+        user_message_str = ujson.dumps(user_message)
+        ws.write_message(ujson.dumps([user_message_str]))
+
+        def wrap_get_response(request: HttpRequest) -> HttpResponse:
+            request._log_data = {'bugdown_requests_start': 0,
+                                 'time_started': 0,
+                                 'bugdown_time_start': 0,
+                                 'remote_cache_time_start': 0,
+                                 'remote_cache_requests_start': 0,
+                                 'startup_time_delta': 0}
+
+            class ResponseObject(object):
+                def __init__(self) -> None:
+                    self.content = '{"msg":"","id":0,"result":"error"}'.encode('utf8')
+            return ResponseObject()
+        # Simulate an error response to cover the respective code paths.
+        with patch('django.core.handlers.base.BaseHandler.get_response', wraps=wrap_get_response), \
+                patch('django.db.connection.is_usable', return_value=False), \
+                patch('os.kill', side_effect=OSError()):
+            yield ws.read_message()
+        yield self.close(ws)