Hi. When integration testing complex forms, that is forms that updates more than one model (through as has_many), and the submodel fields contains file uploads. The mock request generated is incorrect. I have made a ticket (2576) describing the problem. Supplied a patch that contains tests that demonstrates the problems and contains a fix for the problem. See https://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/2576 Hope this will be committed to rails master branch. Jarl