You’re writing a test that involves photo uploading. You use the fixture_file_upload method to generate the data of your :uploaded_data field. Running the test that includes creating a photo object, you get an error:
wrong number of arguments (0 for 1) /vendor/plugins/attachment_fu/lib/technoweenie/attachment_fu.rb:line=351 :in 'content_type' /vendor/plugins/attachment_fu/lib/technoweenie/attachment_fu.rb:line=351 :in 'send' /vendor/plugins/attachment_fu/lib/technoweenie/attachment_fu.rb:line=351 :in 'attachment_attributes_valid?' ...
The error means you called the content_type method of your object with no arguments, when it was expecting 1. It was expecting 1, even though content_type should have been an attribute reader method with no arguments.
Why?
Because when you generated the users_controller_spec.rb using the generator of the Restful Authentication plugin, the comment said you should move the include AuthenticatedTestHelper to spec_helper.rb. And you did. And the AuthenticatedTestHelper module defines a content_type method with 1 argument that gets added to the Object class.
And this is why some people warn you about monkey patching.