Add a linearizer on (appservice, stream) when handling ephemeral events. (#11207)

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

tests/handlers/test_appservice.py

@@ -40,6 +40,7 @@ class AppServiceHandlerTestCase(unittest.TestCase):
         hs.get_application_service_scheduler.return_value = self.mock_scheduler
         hs.get_clock.return_value = MockClock()
         self.handler = ApplicationServicesHandler(hs)
+        self.event_source = hs.get_event_sources()
 
     def test_notify_interested_services(self):
         interested_service = self._mkservice(is_interested=True)
@@ -252,6 +253,56 @@ class AppServiceHandlerTestCase(unittest.TestCase):
             },
         )
 
+    def test_notify_interested_services_ephemeral(self):
+        """
+        Test sending ephemeral events to the appservice handler are scheduled
+        to be pushed out to interested appservices, and that the stream ID is
+        updated accordingly.
+        """
+        interested_service = self._mkservice(is_interested=True)
+        services = [interested_service]
+
+        self.mock_store.get_app_services.return_value = services
+        self.mock_store.get_type_stream_id_for_appservice.return_value = make_awaitable(
+            579
+        )
+
+        event = Mock(event_id="event_1")
+        self.event_source.sources.receipt.get_new_events_as.return_value = (
+            make_awaitable(([event], None))
+        )
+
+        self.handler.notify_interested_services_ephemeral("receipt_key", 580)
+        self.mock_scheduler.submit_ephemeral_events_for_as.assert_called_once_with(
+            interested_service, [event]
+        )
+        self.mock_store.set_type_stream_id_for_appservice.assert_called_once_with(
+            interested_service,
+            "read_receipt",
+            580,
+        )
+
+    def test_notify_interested_services_ephemeral_out_of_order(self):
+        """
+        Test sending out of order ephemeral events to the appservice handler
+        are ignored.
+        """
+        interested_service = self._mkservice(is_interested=True)
+        services = [interested_service]
+
+        self.mock_store.get_app_services.return_value = services
+        self.mock_store.get_type_stream_id_for_appservice.return_value = make_awaitable(
+            580
+        )
+
+        event = Mock(event_id="event_1")
+        self.event_source.sources.receipt.get_new_events_as.return_value = (
+            make_awaitable(([event], None))
+        )
+
+        self.handler.notify_interested_services_ephemeral("receipt_key", 579)
+        self.mock_scheduler.submit_ephemeral_events_for_as.assert_not_called()
+
     def _mkservice(self, is_interested, protocols=None):
         service = Mock()
         service.is_interested.return_value = make_awaitable(is_interested)