How to test if it is working?

Besides I have a visual confirmation of authenticate sites (timed popup at the bottom of the window), how can I test a site without the authentication or where the authentication fail?
Is there a link for this test?

Every site where you don’t get the green frame (depending on your settings)
= Fail or lack of being able to verify.

VE is only an indicator of the positive, and doesn’t prove the negative.


Thanks Bad Frogger.
I had to uninstall CVE as it is crashing my Firefox.
So I can’t see the green frame anymore.
Anyway, a little bit of configurability for the user will be good (to control the visual warnings, for instance).