This happened to me too. It looks like there's a bug here.
What I noticed is that when my functional test controller is made, the
setup method expects a fixture entry called :first to be available.
@controller = WhereisController.new
@request = ActionController::TestRequest.new
@response = ActionController::TestResponse.new
@first_id = whereis(:first).id
However, fixtures only as
# Read about fixtures at http://ar.rubyonrails.org/classes/Fixtures.html
This is new (to me anyway) in Rails 1.2. Traditionally, fixture
contained entries called :first, and :second.
You can get around your problem by changing your test controller to
use :one in the setup method.