Those "Mary Sue" tests forget one veru important sub-species of the Mary Sue species: the Cannon!Sue, or "Mary Sued". This applies for fanfiction, and it's when you take a cannon character (generally your favorite character), and make him/her perfect and overachieving, and all those things a Mary Sue/Gary Stu is.
I tend to do that when writing fanfiction, but then I try to correct myself. I don't really do any of those fancy things people do to their characters of choice, but I tend to make them more aspìe-like, and a lil' crazier.