[CMake] run tests only if BUILD_TESTING

CMakeLists.txt

@@ -35,7 +35,9 @@ IF(BUILD_PYTHON_INTERFACE)
   FINDPYTHON()
   STRING(REGEX REPLACE "-" "_" PY_NAME ${PROJECT_NAME})
   ADD_SUBDIRECTORY(python)
-  ADD_SUBDIRECTORY(unittest)
+  IF(BUILD_TESTING)
+    ADD_SUBDIRECTORY(unittest)
+  ENDIF(BUILD_TESTING)
 ENDIF(BUILD_PYTHON_INTERFACE)
 
 IF(NOT INSTALL_PYTHON_INTERFACE_ONLY)