test: fix lossy_ddl test (#987)

ref #442

downstreamadapter/sink/blackhole.go

@@ -44,7 +44,9 @@ func (s *BlackHoleSink) SetTableSchemaStore(tableSchemaStore *util.TableSchemaSt
 }
 
 func (s *BlackHoleSink) AddDMLEvent(event *commonEvent.DMLEvent) {
-	log.Debug("BlackHoleSink: DML Event", zap.Any("dml", event))
+	// NOTE: don't change the log, integration test `lossy_ddl` depends on it.
+	// ref: https://github.com/pingcap/ticdc/blob/da834db76e0662ff15ef12645d1f37bfa6506d83/tests/integration_tests/lossy_ddl/run.sh#L23
+	log.Debug("BlackHoleSink: WriteEvents", zap.Any("dml", event))
 	for _, callback := range event.PostTxnFlushed {
 		callback()
 	}
@@ -58,6 +60,9 @@ func (s *BlackHoleSink) WriteBlockEvent(event commonEvent.BlockEvent) error {
 	switch event.GetType() {
 	case commonEvent.TypeDDLEvent:
 		e := event.(*commonEvent.DDLEvent)
+		// NOTE: don't change the log, integration test `lossy_ddl` depends on it.
+		// ref: https://github.com/pingcap/ticdc/blob/da834db76e0662ff15ef12645d1f37bfa6506d83/tests/integration_tests/lossy_ddl/run.sh#L17
+		log.Debug("BlackHoleSink: DDL Event", zap.Any("ddl", e))
 		for _, callback := range e.PostTxnFlushed {
 			callback()
 		}