Fire up your console:
rails c
then:
app.get ‘/posts/1’
response = app.response
response.body # if you need the HTML body
response.cookies # if you want a hash of the cookies
Plenty more here:
http://rails.rubyonrails.org/classes/ActionController/Integration/Session.html
and here:
However, if you want to do some serious debugging you’ll probably want to use pry. See an earlier post.