Update CMakeLists.txt

cpp/CMakeLists.txt

diff --git a/cpp/CMakeLists.txt b/cpp/CMakeLists.txt
index 20af9ff..80881db 100644
--- a/cpp/CMakeLists.txt
+++ b/cpp/CMakeLists.txt
@@ -14,4 +14,7 @@
 
 set(SECUREMESSAGE_CPP_ROOT ${CMAKE_CURRENT_LIST_DIR})
 add_subdirectory(src/securemessage)
-add_subdirectory(test/securemessage)
+
+if (NOT BYPASS_TESTING)
+  add_subdirectory(test/securemessage)
+endif()