diff --git a/cpp/src/core/CMakeLists.txt b/cpp/src/core/CMakeLists.txt
index f1a13b452002847dea2898f599898db0d449cdb6..9125f6ea2c5fc2bdedd57533eaeaab341d047561 100644
--- a/cpp/src/core/CMakeLists.txt
+++ b/cpp/src/core/CMakeLists.txt
@@ -95,7 +95,7 @@ endif()
 set(CORE_INCLUDE_DIRS ${CORE_INCLUDE_DIRS} PARENT_SCOPE)
 
 if(BUILD_UNIT_TEST STREQUAL "ON")
-    add_subdirectory(test)
+    add_subdirectory(unittest)
 endif()
 
 config_summary()
diff --git a/cpp/src/core/test/CMakeLists.txt b/cpp/src/core/unittest/CMakeLists.txt
similarity index 98%
rename from cpp/src/core/test/CMakeLists.txt
rename to cpp/src/core/unittest/CMakeLists.txt
index ecb52695bcb6e8336297918ba5059246b3e6b496..6b5775c2cdeef755af1709ef1767e9af5e932508 100644
--- a/cpp/src/core/test/CMakeLists.txt
+++ b/cpp/src/core/unittest/CMakeLists.txt
@@ -30,7 +30,7 @@ set(util_srcs
         ${CORE_SOURCE_DIR}/knowhere/knowhere/adapter/ArrowAdapter.cpp
         ${CORE_SOURCE_DIR}/knowhere/knowhere/common/Exception.cpp
         ${CORE_SOURCE_DIR}/knowhere/knowhere/common/Timer.cpp
-        ${CORE_SOURCE_DIR}/test/utils.cpp
+        ${CORE_SOURCE_DIR}/unittest/utils.cpp
         )
 
 #<IVF-TEST>
diff --git a/cpp/src/core/test/SPTAG.cpp b/cpp/src/core/unittest/SPTAG.cpp
similarity index 100%
rename from cpp/src/core/test/SPTAG.cpp
rename to cpp/src/core/unittest/SPTAG.cpp
diff --git a/cpp/src/core/test/faiss_ori/CMakeLists.txt b/cpp/src/core/unittest/faiss_ori/CMakeLists.txt
similarity index 100%
rename from cpp/src/core/test/faiss_ori/CMakeLists.txt
rename to cpp/src/core/unittest/faiss_ori/CMakeLists.txt
diff --git a/cpp/src/core/test/faiss_ori/gpuresource_test.cpp b/cpp/src/core/unittest/faiss_ori/gpuresource_test.cpp
similarity index 100%
rename from cpp/src/core/test/faiss_ori/gpuresource_test.cpp
rename to cpp/src/core/unittest/faiss_ori/gpuresource_test.cpp
diff --git a/cpp/src/core/test/kdtree.cpp b/cpp/src/core/unittest/kdtree.cpp
similarity index 100%
rename from cpp/src/core/test/kdtree.cpp
rename to cpp/src/core/unittest/kdtree.cpp
diff --git a/cpp/src/core/test/sift.50NN.graph b/cpp/src/core/unittest/sift.50NN.graph
similarity index 100%
rename from cpp/src/core/test/sift.50NN.graph
rename to cpp/src/core/unittest/sift.50NN.graph
diff --git a/cpp/src/core/test/siftsmall_base.fvecs b/cpp/src/core/unittest/siftsmall_base.fvecs
similarity index 100%
rename from cpp/src/core/test/siftsmall_base.fvecs
rename to cpp/src/core/unittest/siftsmall_base.fvecs
diff --git a/cpp/src/core/test/test_idmap.cpp b/cpp/src/core/unittest/test_idmap.cpp
similarity index 99%
rename from cpp/src/core/test/test_idmap.cpp
rename to cpp/src/core/unittest/test_idmap.cpp
index 8bf0d5c8d2e7180aaeed779bfc24a58130ab34e3..9ee4ea732d7b919ce3b7aba262134a662a222132 100644
--- a/cpp/src/core/test/test_idmap.cpp
+++ b/cpp/src/core/unittest/test_idmap.cpp
@@ -23,7 +23,7 @@
 #include "knowhere/index/vector_index/IndexIDMAP.h"
 #include "knowhere/index/vector_index/helpers/Cloner.h"
 
-#include "test/utils.h"
+#include "unittest/utils.h"
 
 namespace {
 
diff --git a/cpp/src/core/test/test_ivf.cpp b/cpp/src/core/unittest/test_ivf.cpp
similarity index 99%
rename from cpp/src/core/test/test_ivf.cpp
rename to cpp/src/core/unittest/test_ivf.cpp
index 9835264bffa3c7ce8d9e355df8d5a115f74d55e0..2aa6937dbe26af916011d4a6ab40c082d3fef4c2 100644
--- a/cpp/src/core/test/test_ivf.cpp
+++ b/cpp/src/core/unittest/test_ivf.cpp
@@ -35,7 +35,7 @@
 #include "knowhere/index/vector_index/IndexIVFSQ.h"
 #include "knowhere/index/vector_index/helpers/Cloner.h"
 
-#include "test/utils.h"
+#include "unittest/utils.h"
 
 namespace {
 
diff --git a/cpp/src/core/test/test_json.cpp b/cpp/src/core/unittest/test_json.cpp
similarity index 100%
rename from cpp/src/core/test/test_json.cpp
rename to cpp/src/core/unittest/test_json.cpp
diff --git a/cpp/src/core/test/test_kdt.cpp b/cpp/src/core/unittest/test_kdt.cpp
similarity index 99%
rename from cpp/src/core/test/test_kdt.cpp
rename to cpp/src/core/unittest/test_kdt.cpp
index 45809bf39668e4b4f9627f6e32bd4b9f51624aaf..85c8650d1b3e4b9c5aa4209c2a3a9b938729b934 100644
--- a/cpp/src/core/test/test_kdt.cpp
+++ b/cpp/src/core/unittest/test_kdt.cpp
@@ -26,7 +26,7 @@
 #include "knowhere/index/vector_index/IndexKDT.h"
 #include "knowhere/index/vector_index/helpers/Definitions.h"
 
-#include "test/utils.h"
+#include "unittest/utils.h"
 
 namespace {
 
diff --git a/cpp/src/core/test/test_nsg.cpp b/cpp/src/core/unittest/test_nsg.cpp
similarity index 100%
rename from cpp/src/core/test/test_nsg.cpp
rename to cpp/src/core/unittest/test_nsg.cpp
diff --git a/cpp/src/core/test/test_nsg/CMakeLists.txt b/cpp/src/core/unittest/test_nsg/CMakeLists.txt
similarity index 100%
rename from cpp/src/core/test/test_nsg/CMakeLists.txt
rename to cpp/src/core/unittest/test_nsg/CMakeLists.txt
diff --git a/cpp/src/core/test/test_nsg/test_nsg.cpp b/cpp/src/core/unittest/test_nsg/test_nsg.cpp
similarity index 99%
rename from cpp/src/core/test/test_nsg/test_nsg.cpp
rename to cpp/src/core/unittest/test_nsg/test_nsg.cpp
index 6f7ca1eba9a28859828cc29cac71a2d9fd021625..b93a2ddc355eeff4165c8f4eabd4faf4cf98616d 100644
--- a/cpp/src/core/test/test_nsg/test_nsg.cpp
+++ b/cpp/src/core/unittest/test_nsg/test_nsg.cpp
@@ -24,7 +24,7 @@
 #include "knowhere/index/vector_index/helpers/FaissGpuResourceMgr.h"
 #include "knowhere/index/vector_index/nsg/NSGIO.h"
 
-#include "test/utils.h"
+#include "unittest/utils.h"
 
 namespace {
 
diff --git a/cpp/src/core/test/utils.cpp b/cpp/src/core/unittest/utils.cpp
similarity index 99%
rename from cpp/src/core/test/utils.cpp
rename to cpp/src/core/unittest/utils.cpp
index a921b698022157cc0e80b9df158ff4773d922f14..e81ad8ea0253cf7668203386acdf76a8e94958e9 100644
--- a/cpp/src/core/test/utils.cpp
+++ b/cpp/src/core/unittest/utils.cpp
@@ -15,7 +15,7 @@
 // specific language governing permissions and limitations
 // under the License.
 
-#include "test/utils.h"
+#include "unittest/utils.h"
 
 #include <memory>
 #include <string>
diff --git a/cpp/src/core/test/utils.h b/cpp/src/core/unittest/utils.h
similarity index 100%
rename from cpp/src/core/test/utils.h
rename to cpp/src/core/unittest/utils.h
diff --git a/cpp/src/wrapper/ConfAdapter.cpp b/cpp/src/wrapper/ConfAdapter.cpp
index df1ac6bb70cb894b9a384f4a7467dd9240cba9f1..09d219b99923e90ffef7836ee48142c714e0411a 100644
--- a/cpp/src/wrapper/ConfAdapter.cpp
+++ b/cpp/src/wrapper/ConfAdapter.cpp
@@ -81,7 +81,7 @@ IVFConfAdapter::MatchNlist(const int64_t& size, const int64_t& nlist) {
         // calculate a proper nlist if nlist not specified or size less than TYPICAL_COUNT
         return int(size / TYPICAL_COUNT * 16384);
     }
-    return 0;
+    return nlist;
 }
 
 knowhere::Config