XEP-0421: add has_feature helper

Signed-off-by: Maxime “pep” Buquet <pep@bouah.net>

slixmpp/plugins/xep_0421/occupant_id.py

@@ -6,7 +6,7 @@
     See the file LICENSE for copying permission.
 """
 
-from slixmpp import Message
+from slixmpp import JID, Message
 from slixmpp.plugins import BasePlugin
 from slixmpp.xmlstream import register_stanza_plugin
 from slixmpp.plugins.xep_0421 import stanza
@@ -18,9 +18,13 @@ class XEP_0421(BasePlugin):
 
     name = 'xep_0421'
     description = 'Anonymous unique occupant identifiers for MUCs'
-    dependencies = {'xep_0045'}
+    dependencies = {'xep_0030', 'xep_0045'}
     stanza = stanza
 
     def plugin_init(self) -> None:
         # XXX: This should be MucMessage. Someday..
         register_stanza_plugin(Message, OccupantId)
+
+    async def has_feature(self, jid: JID) -> bool:
+        info = await self.xmpp['xep_0030'].get_info(jid)
+        return self.stanza.NS in info.get_features()

slixmpp/plugins/xep_0421/stanza.py

@@ -9,6 +9,9 @@
 from slixmpp.xmlstream import ElementBase
 
 
+NS = 'urn:xmpp:occupant-id:0'
+
+
 class OccupantId(ElementBase):
     '''
     An Occupant-id tag.
@@ -33,5 +36,5 @@ class OccupantId(ElementBase):
     '''
 
     name = 'occupant-id'
-    namespace = 'urn:xmpp:occupant-id:0'
+    namespace = NS
     interface = {'id'}