Here's the latest version
http://pastie.caboo.se/154256
I've changed things around a bit, so that it now saves the data to be
tested in the action method of the controller.
Still works when run directly with ruby, and it still fails when run with rake.
Running under rake, the action method in the controller doesn't seem
to be invoked. Still trying to figure out why.
Solved!
The issue was being caused by changes to
ApplicationController::Integration::Session monkey patched in the
existing rails test actionpack/test/controller/integration_test.rb
I've updated my original ticket
http://dev.rubyonrails.org/ticket/11091
with the fixed testcase code.
And opened another ticket
http://dev.rubyonrails.org/ticket/11163
With just the patch to integration_test.rb which I believe should be
fixed regardless of whether the file upload patch is accepted.