I think I tried to take one of those reading tests before. They don't work for me for various reasons. First the texts they offer are not something I would read and when I don't want to read something, my brain wanders of. I also cannot read books of any screens like computers/tablets. Since I do all my browsing on computers, I would have to take such a text on it and again, my brain won't work the same way it does when I read a book on my kindle.
Only thing I would like to be able to is read more books period. Even on a good week when I can read maybe one a day, or one every other day, I still have so many good books I must read before I croak. Its not the reading speed that is an issue with me, its my puny human life span.