Catch-up after Federation Outage (split, 1) (#8230)

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

tests/federation/test_federation_catch_up.py

@@ -0,0 +1,82 @@
+from mock import Mock
+
+from synapse.rest import admin
+from synapse.rest.client.v1 import login, room
+
+from tests.test_utils import event_injection, make_awaitable
+from tests.unittest import FederatingHomeserverTestCase, override_config
+
+
+class FederationCatchUpTestCases(FederatingHomeserverTestCase):
+    servlets = [
+        admin.register_servlets,
+        room.register_servlets,
+        login.register_servlets,
+    ]
+
+    def make_homeserver(self, reactor, clock):
+        return self.setup_test_homeserver(
+            federation_transport_client=Mock(spec=["send_transaction"]),
+        )
+
+    def prepare(self, reactor, clock, hs):
+        # stub out get_current_hosts_in_room
+        state_handler = hs.get_state_handler()
+
+        # This mock is crucial for destination_rooms to be populated.
+        state_handler.get_current_hosts_in_room = Mock(
+            return_value=make_awaitable(["test", "host2"])
+        )
+
+    def get_destination_room(self, room: str, destination: str = "host2") -> dict:
+        """
+        Gets the destination_rooms entry for a (destination, room_id) pair.
+
+        Args:
+            room: room ID
+            destination: what destination, default is "host2"
+
+        Returns:
+            Dictionary of { event_id: str, stream_ordering: int }
+        """
+        event_id, stream_ordering = self.get_success(
+            self.hs.get_datastore().db_pool.execute(
+                "test:get_destination_rooms",
+                None,
+                """
+                SELECT event_id, stream_ordering
+                    FROM destination_rooms dr
+                    JOIN events USING (stream_ordering)
+                    WHERE dr.destination = ? AND dr.room_id = ?
+                """,
+                destination,
+                room,
+            )
+        )[0]
+        return {"event_id": event_id, "stream_ordering": stream_ordering}
+
+    @override_config({"send_federation": True})
+    def test_catch_up_destination_rooms_tracking(self):
+        """
+        Tests that we populate the `destination_rooms` table as needed.
+        """
+        self.register_user("u1", "you the one")
+        u1_token = self.login("u1", "you the one")
+        room = self.helper.create_room_as("u1", tok=u1_token)
+
+        self.get_success(
+            event_injection.inject_member_event(self.hs, room, "@user:host2", "join")
+        )
+
+        event_id_1 = self.helper.send(room, "wombats!", tok=u1_token)["event_id"]
+
+        row_1 = self.get_destination_room(room)
+
+        event_id_2 = self.helper.send(room, "rabbits!", tok=u1_token)["event_id"]
+
+        row_2 = self.get_destination_room(room)
+
+        # check: events correctly registered in order
+        self.assertEqual(row_1["event_id"], event_id_1)
+        self.assertEqual(row_2["event_id"], event_id_2)
+        self.assertEqual(row_1["stream_ordering"], row_2["stream_ordering"] - 1)