rake spec:rcov SHOW_ONLY="app"

I just know from http://cheat.errtheblog.com/s/rcov how to do spec'ing
that excludes ruby libraries we have under vendor directory. So that I
can use it happily ever after.

rake spec:rcov SHOW_ONLY="app"

I can explore rake tasks by typing `rake -T` under ruby project
directory, but for this rake spec:rcov option, how would I know other
options that are available besides SHOW_ONLY ?

Thanks!

http://tinyurl.com/2bjgvn