mention: Allow silent mentioning system user groups.

Previously, we do not allow mentioning system user groups
at all. Now we want to use silent mention syntax for system
groups in the message sent when updating the posting permission
for a stream, so it is important to allowing silent mentioning
system groups at least. And there is no problem in allowing
silent mentions of system groups for all users.

We do not allow mentioning system groups as can_mention_group
for them is set to "Nobody" group.

web/src/rendered_markdown.ts

@@ -212,7 +212,7 @@ export const update_elements = ($content: JQuery): void => {
         if (user_group_id && $(this).find(".highlight").length === 0) {
             // Edit the mention to show the current name for the
             // user group, if its not in search.
-            set_name_in_mention_element(this, user_group.name);
+            set_name_in_mention_element(this, user_groups.get_display_group_name(user_group.name));
         }
     });
 

zerver/lib/markdown/__init__.py

@@ -51,6 +51,7 @@ from zerver.lib.mention import (
     FullNameInfo,
     MentionBackend,
     MentionData,
+    get_user_group_mention_display_name,
 )
 from zerver.lib.outgoing_http import OutgoingSession
 from zerver.lib.subdomains import is_static_or_current_realm_url
@@ -1989,7 +1990,7 @@ class UserGroupMentionPattern(CompiledInlineProcessor):
 
                 if not silent:
                     self.zmd.zulip_rendering_result.mentions_user_group_ids.add(user_group.id)
-                name = user_group.name
+                name = get_user_group_mention_display_name(user_group)
                 user_group_id = str(user_group.id)
             else:
                 # Don't highlight @-mentions that don't refer to a valid user

zerver/lib/mention.py

@@ -5,10 +5,12 @@ from re import Match
 
 from django.conf import settings
 from django.db.models import Q
+from django_stubs_ext import StrPromise
 
 from zerver.lib.user_groups import get_recursive_group_members
 from zerver.lib.users import get_inaccessible_user_ids
 from zerver.models import NamedUserGroup, UserProfile
+from zerver.models.groups import SystemGroups
 from zerver.models.streams import get_linkable_streams
 
 BEFORE_MENTION_ALLOWED_REGEX = r"(?<![^\s\'\"\(\{\[\/<])"
@@ -271,7 +273,7 @@ class MentionData:
         user_group_names = possible_user_group_mentions(content)
         if user_group_names:
             for group in NamedUserGroup.objects.filter(
-                realm_id=realm_id, name__in=user_group_names, is_system_group=False
+                realm_id=realm_id, name__in=user_group_names
             ):
                 self.user_group_name_info[group.name.lower()] = group
                 self.user_group_members[group.id] = [
@@ -308,3 +310,10 @@ class MentionData:
 
 def silent_mention_syntax_for_user(user_profile: UserProfile) -> str:
     return f"@_**{user_profile.full_name}|{user_profile.id}**"
+
+
+def get_user_group_mention_display_name(user_group: NamedUserGroup) -> StrPromise | str:
+    if user_group.is_system_group:
+        return SystemGroups.GROUP_DISPLAY_NAME_MAP[user_group.name]
+
+    return user_group.name

zerver/models/groups.py

@@ -1,6 +1,7 @@
 from django.db import models
 from django.db.models import CASCADE
 from django.utils.timezone import now as timezone_now
+from django.utils.translation import gettext_lazy
 from django_cte import CTEManager
 
 from zerver.lib.types import GroupPermissionSetting
@@ -17,6 +18,17 @@ class SystemGroups:
     EVERYONE = "role:everyone"
     NOBODY = "role:nobody"
 
+    GROUP_DISPLAY_NAME_MAP = {
+        NOBODY: gettext_lazy("Nobody"),
+        OWNERS: gettext_lazy("Owners"),
+        ADMINISTRATORS: gettext_lazy("Administrators"),
+        MODERATORS: gettext_lazy("Moderators"),
+        FULL_MEMBERS: gettext_lazy("Full members"),
+        MEMBERS: gettext_lazy("Members"),
+        EVERYONE: gettext_lazy("Everyone"),
+        EVERYONE_ON_INTERNET: gettext_lazy("Everyone on the internet"),
+    }
+
 
 class UserGroup(models.Model):  # type: ignore[django-manager-missing] # django-stubs cannot resolve the custom CTEManager yet https://github.com/typeddjango/django-stubs/issues/1023
     objects: CTEManager = CTEManager()

zerver/tests/test_markdown.py

@@ -2871,6 +2871,7 @@ class MarkdownMentionTest(ZulipTestCase):
         update_message_and_check_flag("edited", False)
         update_message_and_check_flag("@*support*", True)
         update_message_and_check_flag("@_*support*", False)
+        update_message_and_check_flag("@_*role:administrators*", False)
 
     def test_user_group_mention_invalid(self) -> None:
         sender_user_profile = self.example_user("othello")
@@ -2907,6 +2908,17 @@ class MarkdownMentionTest(ZulipTestCase):
 
         self.assertEqual(rendering_result.mentions_user_group_ids, set())
 
+        admins_group = NamedUserGroup.objects.get(
+            name=SystemGroups.ADMINISTRATORS, realm=sender_user_profile.realm, is_system_group=True
+        )
+        content = "Please contact @_*role:administrators*"
+        rendering_result = render_message_markdown(msg, content)
+        self.assertEqual(
+            rendering_result.rendered_content,
+            "<p>Please contact "
+            f'<span class="user-group-mention silent" data-user-group-id="{admins_group.id}">Administrators</span></p>',
+        )
+
     def test_deactivated_user_group_mention(self) -> None:
         sender_user_profile = self.example_user("othello")
         msg = Message(
@@ -2950,27 +2962,6 @@ class MarkdownMentionTest(ZulipTestCase):
         assert_silent_mention("```quote\n@*backend*\n```")
         assert_silent_mention("```quote\n@_*backend*\n```")
 
-    def test_system_user_group_mention(self) -> None:
-        desdemona = self.example_user("desdemona")
-        iago = self.example_user("iago")
-        hamlet = self.example_user("hamlet")
-        moderators_group = NamedUserGroup.objects.get(
-            realm=iago.realm, name=SystemGroups.MODERATORS, is_system_group=True
-        )
-        content = "@*role:moderators* @**King Hamlet** test message"
-
-        # Owner cannot mention a system user group.
-        msg = Message(sender=desdemona, sending_client=get_client("test"), realm=desdemona.realm)
-        rendering_result = render_message_markdown(msg, content)
-        self.assertEqual(rendering_result.mentions_user_ids, {hamlet.id})
-        self.assertNotIn(moderators_group.id, rendering_result.mentions_user_group_ids)
-
-        # Admin belonging to user group also cannot mention a system user group.
-        msg = Message(sender=iago, sending_client=get_client("test"), realm=iago.realm)
-        rendering_result = render_message_markdown(msg, content)
-        self.assertEqual(rendering_result.mentions_user_ids, {hamlet.id})
-        self.assertNotIn(moderators_group.id, rendering_result.mentions_user_group_ids)
-
 
 class MarkdownStreamMentionTests(ZulipTestCase):
     def test_stream_single(self) -> None:

zerver/tests/test_message_send.py

@@ -2322,6 +2322,25 @@ class StreamMessagesTest(ZulipTestCase):
         result = self.api_get(cordelia, "/api/v1/messages/" + str(msg_id))
         self.assert_json_success(result)
 
+        # Test mentioning system groups where can_mention_group is
+        # set to "Nobody" group.
+        self.assertEqual(
+            moderators_system_group.can_mention_group.named_user_group.name, SystemGroups.NOBODY
+        )
+        content = "Test mentioning user group @*role:moderators*"
+
+        with self.assertRaisesRegex(
+            JsonableError,
+            f"You are not allowed to mention user group '{moderators_system_group.name}'.",
+        ):
+            self.send_stream_message(iago, "test_stream", content)
+
+        # silent mentioning system groups is allowed.
+        content = "Test mentioning user group @_*role:moderators*"
+        msg_id = self.send_stream_message(iago, "test_stream", content)
+        result = self.api_get(cordelia, "/api/v1/messages/" + str(msg_id))
+        self.assert_json_success(result)
+
     def test_stream_message_mirroring(self) -> None:
         user = self.mit_user("starnine")
         self.subscribe(user, "Verona")