cheat sheets.

assert_no_difference -- an assertion for your testing suite

Usage:
  assert_no_difference 'Model.count' do
    puts "blah"
  end

Synonym for:
  assert_difference 'Model.count', 0 do
    puts "blah" #or any action that will NOT change the argument.
  end

This is useful for when you are testing benign actions or, even better, when you
have fail-safes that allow an action to be executed but do not actually affect
the database.
For instance, you've got an action that is protected by authentication and you
don't want to broadcast its existance to anyone with lesser permissions.  If an
unauthenticated
use navigates to the action, just let them see nothing (render :nothing => true
or something to that effect) and chug along without caring.