diff --git a/tests/handlers/test_federation.py b/tests/handlers/test_federation.py
index 936ebf3dde..e1557566e4 100644
--- a/tests/handlers/test_federation.py
+++ b/tests/handlers/test_federation.py
@@ -23,6 +23,7 @@ from synapse.federation.federation_base import event_from_pdu_json
from synapse.logging.context import LoggingContext, run_in_background
from synapse.rest import admin
from synapse.rest.client import login, room
+from synapse.types import create_requester
from synapse.util.stringutils import random_string
from tests import unittest
@@ -30,6 +31,10 @@ from tests import unittest
logger = logging.getLogger(__name__)
+def generate_fake_event_id() -> str:
+ return "$fake_" + random_string(43)
+
+
class FederationTestCase(unittest.HomeserverTestCase):
servlets = [
admin.register_servlets,
@@ -198,6 +203,65 @@ class FederationTestCase(unittest.HomeserverTestCase):
self.assertEqual(sg, sg2)
+ def test_backfill_with_many_backward_extremities(self):
+ """
+ Check that we can backfill with many backward extremities.
+ The goal is to make sure that when we only use a portion
+ of backwards extremities(the magic number is more than 5),
+ no errors are thrown.
+
+ Regression test, see #11027
+ """
+ # create the room
+ user_id = self.register_user("kermit", "test")
+ tok = self.login("kermit", "test")
+ requester = create_requester(user_id)
+
+ room_id = self.helper.create_room_as(room_creator=user_id, tok=tok)
+
+ ev1 = self.helper.send(room_id, "first message", tok=tok)
+
+ # Create "many" backward extremities. The magic number we're trying to
+ # create more than is 5 which corresponds to the number of backward
+ # extremities we slice off in `_maybe_backfill_inner`
+ for _ in range(0, 8):
+ event_handler = self.hs.get_event_creation_handler()
+ event, context = self.get_success(
+ event_handler.create_event(
+ requester,
+ {
+ "type": "m.room.message",
+ "content": {
+ "msgtype": "m.text",
+ "body": "message connected to fake event",
+ },
+ "room_id": room_id,
+ "sender": user_id,
+ },
+ prev_event_ids=[
+ ev1["event_id"],
+ # We're creating an backward extremity each time thanks
+ # to this fake event
+ generate_fake_event_id(),
+ ],
+ )
+ )
+ self.get_success(
+ event_handler.handle_new_client_event(requester, event, context)
+ )
+
+ current_depth = 1
+ limit = 100
+ with LoggingContext("receive_pdu"):
+ # Make sure backfill still works
+ d = run_in_background(
+ self.hs.get_federation_handler().maybe_backfill,
+ room_id,
+ current_depth,
+ limit,
+ )
+ self.get_success(d)
+
def test_backfill_floating_outlier_membership_auth(self):
"""
As the local homeserver, check that we can properly process a federated
|
