fix broken test

tests/storage/test_event_chain.py

@@ -20,6 +20,7 @@
 from synapse.api.constants import EventTypes
 from synapse.api.room_versions import RoomVersions
 from synapse.events import EventBase
+from synapse.events.snapshot import EventContext
 from synapse.rest import admin
 from synapse.rest.client.v1 import login, room
 from synapse.storage.databases.main.events import _LinkMap
@@ -388,7 +389,9 @@ def persist(
         def _persist(txn):
             # We need to persist the events to the events and state_events
             # tables.
-            persist_events_store._store_event_txn(txn, [(e, {}) for e in events])
+            persist_events_store._store_event_txn(
+                txn, [(e, EventContext()) for e in events]
+            )
 
             # Actually call the function that calculates the auth chain stuff.
             persist_events_store._persist_event_auth_chain_txn(txn, events)