This is as far as I know a browser based limitation, due to concerns of
security and privacy.
is not allowed to clear all cookies (think how nasty that could be on a
malicious site). In the non testing env, most JS that is executing came
from the server of the site you are accessing. So the most it is allowed
to do is clear the cookies for the 'current domain' e.g. the cookies
belonging to the current URL. So if a web page wants to clear all its own
cookies, that is OK, but it is not allowed to clear cookies belonging to
So if you want all your tests to start with fresh cookies, you will need
something in the 'Before' section in env.rb that goes to the root of the
site in question, and then clears the cookies
BTW the same limitation applies to setting cookies, if you want to
create cookies for a specific site, you need to navigate to that site
before trying to create them, or nothing gets created.