diff --git a/tests/handlers/test_sync.py b/tests/handlers/test_sync.py
index 5d8e886541..57e14d79ca 100644
--- a/tests/handlers/test_sync.py
+++ b/tests/handlers/test_sync.py
@@ -435,6 +435,111 @@ class SyncTestCase(tests.unittest.HomeserverTestCase):
[s2_event],
)
+ def test_state_includes_changes_on_ungappy_syncs(self) -> None:
+ """Test `state` where the sync is not gappy.
+
+ We start with a DAG like this:
+
+ E1
+ ↗ ↖
+ | S2
+ |
+ --|---
+ |
+ E3
+
+ ... and initialsync with `limit=1`, represented by the horizontal dashed line.
+ At this point, we do not expect S2 to appear in the response at all (since
+ it is excluded from the timeline by the `limit`, and the state is based on the
+ state after the most recent event before the sync token (E3), which doesn't
+ include S2.
+
+ Now more events arrive, and we do an incremental sync:
+
+ E1
+ ↗ ↖
+ | S2
+ | ↑
+ E3 |
+ ↑ |
+ --|------|----
+ | |
+ E4 |
+ ↖ /
+ E5
+
+ This is the last chance for us to tell the client about S2, so it *must* be
+ included in the response.
+ """
+ alice = self.register_user("alice", "password")
+ alice_tok = self.login(alice, "password")
+ alice_requester = create_requester(alice)
+ room_id = self.helper.create_room_as(alice, is_public=True, tok=alice_tok)
+
+ # Do an initial sync to get a known starting point.
+ initial_sync_result = self.get_success(
+ self.sync_handler.wait_for_sync_for_user(
+ alice_requester, generate_sync_config(alice)
+ )
+ )
+ last_room_creation_event_id = (
+ initial_sync_result.joined[0].timeline.events[-1].event_id
+ )
+
+ # Send a state event, and a regular event, both using the same prev ID
+ with self._patch_get_latest_events([last_room_creation_event_id]):
+ s2_event = self.helper.send_state(room_id, "s2", {}, tok=alice_tok)[
+ "event_id"
+ ]
+ e3_event = self.helper.send(room_id, "e3", tok=alice_tok)["event_id"]
+
+ # Another initial sync, with limit=1
+ initial_sync_result = self.get_success(
+ self.sync_handler.wait_for_sync_for_user(
+ alice_requester,
+ generate_sync_config(
+ alice,
+ filter_collection=FilterCollection(
+ self.hs, {"room": {"timeline": {"limit": 1}}}
+ ),
+ ),
+ )
+ )
+ room_sync = initial_sync_result.joined[0]
+ self.assertEqual(room_sync.room_id, room_id)
+ self.assertEqual(
+ [e.event_id for e in room_sync.timeline.events],
+ [e3_event],
+ )
+ self.assertNotIn(s2_event, [e.event_id for e in room_sync.state.values()])
+
+ # More events, E4 and E5
+ with self._patch_get_latest_events([e3_event]):
+ e4_event = self.helper.send(room_id, "e4", tok=alice_tok)["event_id"]
+ e5_event = self.helper.send(room_id, "e5", tok=alice_tok)["event_id"]
+
+ # Now incremental sync
+ incremental_sync = self.get_success(
+ self.sync_handler.wait_for_sync_for_user(
+ alice_requester,
+ generate_sync_config(alice),
+ since_token=initial_sync_result.next_batch,
+ )
+ )
+
+ # The state event should appear in the 'state' section of the response.
+ room_sync = incremental_sync.joined[0]
+ self.assertEqual(room_sync.room_id, room_id)
+ self.assertFalse(room_sync.timeline.limited)
+ self.assertEqual(
+ [e.event_id for e in room_sync.timeline.events],
+ [e4_event, e5_event],
+ )
+ self.assertEqual(
+ [e.event_id for e in room_sync.state.values()],
+ [s2_event],
+ )
+
@parameterized.expand(
[
(False, False),
|
