cmake: look for testing dependencies

CMakeLists.txt

@@ -81,9 +81,7 @@ set (BUILD_TESTING TRUE CACHE BOOL "compile and run unit tests")
 
 # Required dependencies
 set(BOOST_COMPONENTS thread date_time system)
-if (BUILD_TESTING)
-  set(BOOST_COMPONENTS ${BOOST_COMPONENTS} filesystem unit_test_framework chrono)
-endif ()
+set(BOOST_COMPONENTS ${BOOST_COMPONENTS} filesystem unit_test_framework chrono)
 if (BUILD_PYTHON_INTERFACE)
   FINDPYTHON()
   set(BOOST_COMPONENTS ${BOOST_COMPONENTS} python)