Pass lazy loading filter to sync reqs in room summary tests

This aligns correctly with the spec and is also seemingly the only reason
the test is disabled on synapse, now re-enabled.

tests/csapi/sync_test.go

@@ -434,19 +434,33 @@ func TestPresenceSyncDifferentRooms(t *testing.T) {
 	})
 }
 
+func getLazyLoadingSyncFilter() string {
+	j, _ := json.Marshal(map[string]interface{}{
+		"room": map[string]interface{}{
+			"timeline": map[string]interface{}{
+				"lazy_load_members": true,
+			},
+			"state": map[string]interface{}{
+				"lazy_load_members": true,
+			},
+		},
+	})
+	return string(j)
+}
+
 func TestRoomSummary(t *testing.T) {
-	runtime.SkipIf(t, runtime.Synapse) // Currently more of a Dendrite test, so skip on Synapse
 	deployment := Deploy(t, b.BlueprintOneToOneRoom)
 	defer deployment.Destroy(t)
 	alice := deployment.Client(t, "hs1", "@alice:hs1")
 	bob := deployment.Client(t, "hs1", "@bob:hs1")
+	lazyLoadingFilter := getLazyLoadingSyncFilter()
 
-	_, aliceSince := alice.MustSync(t, client.SyncReq{TimeoutMillis: "0"})
+	_, aliceSince := alice.MustSync(t, client.SyncReq{TimeoutMillis: "0", Filter: lazyLoadingFilter})
 	roomID := alice.CreateRoom(t, map[string]interface{}{
 		"preset": "public_chat",
 		"invite": []string{bob.UserID},
 	})
-	aliceSince = alice.MustSyncUntil(t, client.SyncReq{Since: aliceSince},
+	aliceSince = alice.MustSyncUntil(t, client.SyncReq{Since: aliceSince, Filter: lazyLoadingFilter},
 		client.SyncJoinedTo(alice.UserID, roomID),
 		func(clientUserID string, syncResp gjson.Result) error {
 			summary := syncResp.Get("rooms.join." + client.GjsonEscape(roomID) + ".summary")
@@ -471,12 +485,12 @@ func TestRoomSummary(t *testing.T) {
 		return nil
 	}
 
-	sinceToken := bob.MustSyncUntil(t, client.SyncReq{}, client.SyncInvitedTo(bob.UserID, roomID))
+	sinceToken := bob.MustSyncUntil(t, client.SyncReq{Filter: lazyLoadingFilter}, client.SyncInvitedTo(bob.UserID, roomID))
 	bob.JoinRoom(t, roomID, []string{})
 	// Verify Bob sees the correct room summary
-	bob.MustSyncUntil(t, client.SyncReq{Since: sinceToken}, client.SyncJoinedTo(bob.UserID, roomID), joinedCheck)
+	bob.MustSyncUntil(t, client.SyncReq{Since: sinceToken, Filter: lazyLoadingFilter}, client.SyncJoinedTo(bob.UserID, roomID), joinedCheck)
 	// .. and Alice as well.
-	alice.MustSyncUntil(t, client.SyncReq{Since: aliceSince}, client.SyncJoinedTo(bob.UserID, roomID), joinedCheck)
+	alice.MustSyncUntil(t, client.SyncReq{Since: aliceSince, Filter: lazyLoadingFilter}, client.SyncJoinedTo(bob.UserID, roomID), joinedCheck)
 }
 
 func sendMessages(t *testing.T, client *client.CSAPI, roomID string, prefix string, count int) {