test_messages: Fix strict_optional errors.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

mypy.ini

@@ -40,8 +40,6 @@ strict_optional = True
 
 # Tests (may be many issues in file; comment is just one error noted)
 
-[mypy-zerver/tests/test_messages]  #3070: error: Incompatible types in assignment (expression has type "None", variable has type "int")
-strict_optional = False
 [mypy-zerver/tests/test_events]  #1365: error: Argument 2 to "do_set_realm_notifications_stream" has incompatible type "Optional[Stream]"; expected "Stream"
 strict_optional = False
 

zerver/lib/actions.py

@@ -2392,9 +2392,6 @@ def _internal_prep_message(realm: Realm,
     if len(content) > MAX_MESSAGE_LENGTH:
         content = content[0:3900] + "\n\n[message was too long and has been truncated]"
 
-    if realm is None:
-        raise RuntimeError("None is not a valid realm for internal_prep_message!")
-
     # If we have a stream name, and the stream doesn't exist, we
     # create it here (though this code path should probably be removed
     # eventually, moving that responsibility to the caller).  If

zerver/tests/test_messages.py

@@ -2,7 +2,7 @@ import datetime
 import time
 from collections import namedtuple
 from operator import itemgetter
-from typing import Any, Dict, List, Set, Tuple, Union
+from typing import Any, Dict, List, Optional, Set, Tuple, Union
 from unittest import mock
 
 import ujson
@@ -599,16 +599,10 @@ class InternalPrepTest(ZulipTestCase):
             sender=sender,
             recipient_user=recipient_user,
             content=content)
+        assert result is not None
         message = result['message']
         self.assertIn('message was too long', message.content)
 
-        with self.assertRaises(RuntimeError):
-            internal_prep_private_message(
-                realm=None,  # should cause error
-                sender=sender,
-                recipient_user=recipient_user,
-                content=content)
-
         # Simulate sending a message to somebody not in the
         # realm of the sender.
         recipient_user = self.mit_user('starnine')
@@ -1597,7 +1591,7 @@ class SewMessageAndReactionTest(ZulipTestCase):
 
 class MessagePOSTTest(ZulipTestCase):
 
-    def _send_and_verify_message(self, user: UserProfile, stream_name: str, error_msg: str=None) -> None:
+    def _send_and_verify_message(self, user: UserProfile, stream_name: str, error_msg: Optional[str]=None) -> None:
         if error_msg is None:
             msg_id = self.send_stream_message(user, stream_name)
             result = self.api_get(user, '/json/messages/' + str(msg_id))
@@ -2397,6 +2391,7 @@ class MessagePOSTTest(ZulipTestCase):
         self.assert_json_error_contains(result, 'Not authorized to send')
 
         # We subscribe the bot owner! (aka cordelia)
+        assert bot.bot_owner is not None
         self.subscribe(bot.bot_owner, stream_name)
 
         result = self.api_post(bot, "/api/v1/messages", payload)