fixture_file_upload in Integration tests: is it been broken for two years?

Hi everyone,

I'm trying to test file uploads (with attachment_fu) in the
integration tests for a rails 2.0.1 application, with code like:

  post :action, :data => fixture_file_upload('/image.png', 'image/
png')
  assert_response :redirect

but this fails with a message
NoMethodError (undefined method `content_type' for
"#<ActionController::TestUploadedFile:0xb6f1a28c>":String):

because the TestUploadFile object is converted to a String with #to_s
in #requestify (integration.rb about line 337). Obviously,
attachment_fu shows this error but the string conversion problem is
general.

I guess TestUploadedFile should be kept in the parameters hash as-is
instead of being converted to #inspect-Strings.

I hope I'm doing something wrong (i.e. there is an argument to post
that I'm missing).
If not, shall it be specified in the documentation for
fixture_file_upload that this does not work with integration tests?
There has been a ticket about it for 2 years, now[1].

[1] http://dev.rubyonrails.org/ticket/4635