widgets: Remove ALLOW_SUB_MESSAGES flag and enable widgets by default.

docs/subsystems/widgets.md

@@ -34,7 +34,6 @@ messages).
 Here are some code entities used in the above
 features:
 
-- `ALLOW_SUB_MESSAGES` setting
 - `SubMessage` database table
 - `/json/zcommand` API endpoint
 - `/json/submessage` API endpoint
@@ -109,13 +108,10 @@ launch widgets by sending one of the following messages:
 - /todo
 - /tictactoe
 
-These widgets are only turned on if you set the `ALLOW_SUB_MESSAGES`
-boolean to `True` in the appropriate `settings.py`.
-Currently the setting is only enabled for dev and
-our main community realm (chat.zulip.org).  Also,
-only the webapp client provides the "widget experience".
-Other clients just show raw messages like "/poll"
-or "/ticactoe".
+The webapp client provides the "widget experience" by
+default. Other clients just show raw messages like
+"/poll" or "/ticactoe", and should be adding support
+for widgets soon.
 
 Our customers have long requested a poll/survey widget.
 See [this issue](https://github.com/zulip/zulip/issues/9736).
@@ -301,8 +297,7 @@ and grades the answer using ordinary chat-bot coding.
 The beautiful thing is that any thrid party developer
 can enhance bots that are similar to the **trivia_quiz**
 bot without touching any Zulip code, because **zforms**
-are completely generic.  (The only caveat is that
-the server must turn on `ALLOW_SUB_MESSAGES`.)
+are completely generic.
 
 ## Data flow
 

zerver/lib/widget.py

@@ -46,11 +46,9 @@ def get_extra_data_from_widget_type(content: str,
 
 def do_widget_post_save_actions(message: MutableMapping[str, Any]) -> None:
     '''
-    This is experimental code that only works with the
-    webapp for now.
+    This code works with the webapp; mobile and other
+    clients should also start supporting this soon.
     '''
-    if not settings.ALLOW_SUB_MESSAGES:
-        return
     content = message['message'].content
     sender_id = message['message'].sender_id
     message_id = message['message'].id

zerver/tests/test_widgets.py

@@ -232,12 +232,3 @@ class WidgetContentTestCase(ZulipTestCase):
         submessage = SubMessage.objects.get(message_id=message.id)
         self.assertEqual(submessage.msg_type, 'widget')
         self.assertEqual(ujson.loads(submessage.content), expected_submessage_content)
-
-        # Now test the feature flag.
-        with self.settings(ALLOW_SUB_MESSAGES=False):
-            result = self.api_post(sender_email, "/api/v1/messages", payload)
-        self.assert_json_success(result)
-
-        message = self.get_last_message()
-        self.assertEqual(message.content, content)
-        self.assertFalse(SubMessage.objects.filter(message_id=message.id).exists())

zerver/views/submessage.py

@@ -27,10 +27,6 @@ def process_submessage(request: HttpRequest,
                        ) -> HttpResponse:
     message, user_message = access_message(user_profile, message_id)
 
-    if not settings.ALLOW_SUB_MESSAGES:  # nocoverage
-        msg = 'Feature not enabled'
-        return json_error(msg)
-
     try:
         ujson.loads(content)
     except Exception:

zproject/settings.py

@@ -246,10 +246,6 @@ DEFAULT_SETTINGS = {
     # In-development search pills feature.
     'SEARCH_PILLS_ENABLED': False,
 
-    # We use SubMessage for now-experimental features like
-    # slash commands.
-    'ALLOW_SUB_MESSAGES': DEVELOPMENT,
-
     # We log emails in development environment for accessing
     # them easily through /emails page
     'DEVELOPMENT_LOG_EMAILS': DEVELOPMENT,