diff --git a/pyengine/engine/controller/tests/test_scheduler.py b/pyengine/engine/controller/tests/test_scheduler.py
new file mode 100644
index 0000000000..98d2fe373e
--- /dev/null
+++ b/pyengine/engine/controller/tests/test_scheduler.py
@@ -0,0 +1,3 @@
+import unittest
+from ..scheduler import *
+
diff --git a/pyengine/engine/controller/vector_engine.py b/pyengine/engine/controller/vector_engine.py
index b169ae551e..b4847936d7 100644
--- a/pyengine/engine/controller/vector_engine.py
+++ b/pyengine/engine/controller/vector_engine.py
@@ -98,7 +98,8 @@ class VectorEngine(object):
 
                 # create index
                 index_builder = build_index.FactoryIndex()
-                index = index_builder().build(d, raw_data)
+                index = index_builder().build(d, raw_data) # type: index
+                index = build_index.Index.serialize(index) # type: array
 
                 # TODO(jinhai): store index into Cache
                 index_filename = file.filename + '_index'