Not necessarily. Use patch mode (or a tool like GitX that does the same job), commit, then stash and run your tests. If it's broken, amend your commit, rinse and repeat. Then push your changes or pop the stash and continue development.
> without stashing everything else
and noted that if you're going to stash the rest either way you could just as well use `stash -p` in the first place.
There's a difference between `stash -p` and `add -p + stash`, though. If you want to split your changes into more than two commits, you have to use add/commit/add/commit because stash will just make a commit with "what's left" (it's subtractive operation).