Fix catchup-on-reconnect for the Federation Stream (#7374)

looks like we managed to break this during the refactorathon.

tests/replication/tcp/streams/test_federation.py

@@ -0,0 +1,81 @@
+# -*- coding: utf-8 -*-
+# Copyright 2019 New Vector Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from synapse.federation.send_queue import EduRow
+from synapse.replication.tcp.streams.federation import FederationStream
+
+from tests.replication.tcp.streams._base import BaseStreamTestCase
+
+
+class FederationStreamTestCase(BaseStreamTestCase):
+    def _get_worker_hs_config(self) -> dict:
+        # enable federation sending on the worker
+        config = super()._get_worker_hs_config()
+        # TODO: make it so we don't need both of these
+        config["send_federation"] = True
+        config["worker_app"] = "synapse.app.federation_sender"
+        return config
+
+    def test_catchup(self):
+        """Basic test of catchup on reconnect
+
+        Makes sure that updates sent while we are offline are received later.
+        """
+        fed_sender = self.hs.get_federation_sender()
+        received_rows = self.test_handler.received_rdata_rows
+
+        fed_sender.build_and_send_edu("testdest", "m.test_edu", {"a": "b"})
+
+        self.reconnect()
+        self.reactor.advance(0)
+
+        # check we're testing what we think we are: no rows should yet have been
+        # received
+        self.assertEqual(received_rows, [])
+
+        # We should now see an attempt to connect to the master
+        request = self.handle_http_replication_attempt()
+        self.assert_request_is_get_repl_stream_updates(request, "federation")
+
+        # we should have received an update row
+        stream_name, token, row = received_rows.pop()
+        self.assertEqual(stream_name, "federation")
+        self.assertIsInstance(row, FederationStream.FederationStreamRow)
+        self.assertEqual(row.type, EduRow.TypeId)
+        edurow = EduRow.from_data(row.data)
+        self.assertEqual(edurow.edu.edu_type, "m.test_edu")
+        self.assertEqual(edurow.edu.origin, self.hs.hostname)
+        self.assertEqual(edurow.edu.destination, "testdest")
+        self.assertEqual(edurow.edu.content, {"a": "b"})
+
+        self.assertEqual(received_rows, [])
+
+        # additional updates should be transferred without an HTTP hit
+        fed_sender.build_and_send_edu("testdest", "m.test1", {"c": "d"})
+        self.reactor.advance(0)
+        # there should be no http hit
+        self.assertEqual(len(self.reactor.tcpClients), 0)
+        # ... but we should have a row
+        self.assertEqual(len(received_rows), 1)
+
+        stream_name, token, row = received_rows.pop()
+        self.assertEqual(stream_name, "federation")
+        self.assertIsInstance(row, FederationStream.FederationStreamRow)
+        self.assertEqual(row.type, EduRow.TypeId)
+        edurow = EduRow.from_data(row.data)
+        self.assertEqual(edurow.edu.edu_type, "m.test1")
+        self.assertEqual(edurow.edu.origin, self.hs.hostname)
+        self.assertEqual(edurow.edu.destination, "testdest")
+        self.assertEqual(edurow.edu.content, {"c": "d"})