diff --git a/internal/querynode/query_node_test.go b/internal/querynode/query_node_test.go
index ea5dc4d670..5cd1a1ee75 100644
--- a/internal/querynode/query_node_test.go
+++ b/internal/querynode/query_node_test.go
@@ -30,6 +30,7 @@ import (
 	"github.com/milvus-io/milvus/internal/types"
 )
 
+// mock of query coordinator client
 type queryCoordMock struct {
 	types.QueryCoord
 }