Update plugin: XEP-0317 (hats)

Merge changes from nicoco's MR that I missed, improving tests and
interface.

slixmpp/plugins/xep_0317/hats.py

@@ -1,6 +1,4 @@
 from slixmpp.plugins import BasePlugin
-from slixmpp import Presence
-from slixmpp.xmlstream import register_stanza_plugin
 from . import stanza
 
 
@@ -8,13 +6,11 @@ class XEP_0317(BasePlugin):
     """
     XEP-0317: Hats
     """
-
     name = 'xep_0317'
     description = 'XEP-0317: Hats'
-    dependencies = {'xep_0030', 'xep_0050'}
+    dependencies = {'xep_0030', 'xep_0045', 'xep_0050'}
     stanza = stanza
     namespace = stanza.NS
 
     def plugin_init(self):
-        register_stanza_plugin(stanza.Hat, stanza.Hats)
-        register_stanza_plugin(stanza.Hats, Presence)
+        stanza.register_plugin()

slixmpp/plugins/xep_0317/stanza.py

@@ -1,4 +1,5 @@
-from slixmpp.xmlstream import ElementBase
+from slixmpp import Presence
+from slixmpp.xmlstream import ElementBase, register_stanza_plugin
 
 NS = 'urn:xmpp:hats:0'
 
@@ -25,6 +26,13 @@ class Hats(ElementBase):
     namespace = NS
     plugin_attrib = 'hats'
 
+    def add_hats(self, data: list[tuple[str, str]]) -> None:
+        for uri, title in data:
+            hat = Hat()
+            hat["uri"] = uri
+            hat["title"] = title
+            self.append(hat)
+
 
 class Hat(ElementBase):
     """
@@ -38,6 +46,12 @@ class Hat(ElementBase):
 
     """
     name = 'hat'
-    namespace = NS
     plugin_attrib = 'hat'
+    namespace = NS
     interfaces = {'title', 'uri'}
+    plugin_multi_attrib = "hats"
+
+
+def register_plugin() -> None:
+    register_stanza_plugin(Hats, Hat, iterable=True)
+    register_stanza_plugin(Presence, Hats)