params, before_filter and functional test

hi there,
I have a before_filter which does some date formatting on create and
update. This works fine live but it's failing in the tests:

http://pastie.caboo.se/75968

I'm not really sure why that would be the case. This is also my first
proper attempt at writing tests - the value of which I'm immediately
appreciating!

any help would be great, thanks