You can test on Beta (http://en.wikipedia.beta.wmflabs.org/) by editing your preferences (success), going to Special:UserLogin while logged in (warning), and entering the wrong password for login (error).
For grins, enter valid/invalid e-mail... you get weird green and pink client-side validation "strips" (and the browser's own type="email" HTM5 validation warning when you submit).
I filed bug 56363.
Improving this ancient form could be a nice OPW job.