Fix bug where read-receipts lost their timestamps (#4927)

Make sure that they are sent correctly over the replication stream.

Fixes: #4898

tests/replication/tcp/streams/test_receipts.py

@@ -0,0 +1,46 @@
+# -*- 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.replication.tcp.streams import ReceiptsStreamRow
+
+from tests.replication.tcp.streams._base import BaseStreamTestCase
+
+USER_ID = "@feeling:blue"
+ROOM_ID = "!room:blue"
+EVENT_ID = "$event:blue"
+
+
+class ReceiptsStreamTestCase(BaseStreamTestCase):
+    def test_receipt(self):
+        # make the client subscribe to the receipts stream
+        self.replicate_stream("receipts", "NOW")
+
+        # tell the master to send a new receipt
+        self.get_success(
+            self.hs.get_datastore().insert_receipt(
+                ROOM_ID, "m.read", USER_ID, [EVENT_ID], {"a": 1}
+            )
+        )
+        self.replicate()
+
+        # there should be one RDATA command
+        rdata_rows = self.test_handler.received_rdata_rows
+        self.assertEqual(1, len(rdata_rows))
+        self.assertEqual(rdata_rows[0][0], "receipts")
+        row = rdata_rows[0][2]  # type: ReceiptsStreamRow
+        self.assertEqual(ROOM_ID, row.room_id)
+        self.assertEqual("m.read", row.receipt_type)
+        self.assertEqual(USER_ID, row.user_id)
+        self.assertEqual(EVENT_ID, row.event_id)
+        self.assertEqual({"a": 1}, row.data)