Refactor resolve_state_groups_for_events to not pull out full state when no state resolution happens. (#12775)

tests/test_state.py

@@ -129,6 +129,19 @@ class _DummyStore:
     async def get_room_version_id(self, room_id):
         return RoomVersions.V1.identifier
 
+    async def get_state_group_for_events(self, event_ids):
+        res = {}
+        for event in event_ids:
+            res[event] = self._event_to_state_group[event]
+        return res
+
+    async def get_state_for_groups(self, groups):
+        res = {}
+        for group in groups:
+            state = self._group_to_state[group]
+            res[group] = state
+        return res
+
 
 class DictObj(dict):
     def __init__(self, **kwargs):