Would it be possible to make the add_directory(test) dependent on the value of BUILD_TESTING so it can be disabled? Unless there is already a way to switch off testing, it would be helpful to be able to disable it especially given that it attempts to download the fix files. As I recall, BUILD_TESTING is created by include(CTest), so something like the following should work:

include(CTest)
if(BUILD_TESTING)
  add_subdirectory(test)
endif()

If this sounds OK I'm happy to contribute the changes.