I hate to be critical in a terribly ad hominem way, but I find programming/tech articles written in that '13 year old boy who has had a little too much fizzy pop to drink' style with the 'hilarious' l33t-speak aren't really helping eliminate some of the more negative preconceptions of us hackers out there.
I don't know ruby but it appears he didn't write a code coverage tool as the title says but rather formatted the output from the built in code coverage tool into html.