rack test error running paperclip rspec and accepts_nested_attributes_for

gistfile1.rb

#Association Mismatch occurs when trying to create a project using Factory Girl:

Failures:

  1) Project#address_city should works
     Failure/Error: create(:project).address_city.should be_nil
     ActiveRecord::AssociationTypeMismatch:
       ProjectImage(#70115373883740) expected, got Rack::Test::UploadedFile(#70115311431900)
     # ./spec/models/project_spec.rb:194:in `block (3 levels) in <top (required)>'

Finished in 2.66 seconds
1 example, 1 failure

#What I changed the factory to:

FactoryGirl.define do
  factory :project do |f|
    f.status "Completed"
    f.title {Randgen.word}
    f.brand {FactoryGirl.create :designer}
    f.body {Randgen.sentence}
    f.user {FactoryGirl.create(:user)}
    f.images [Rack::Test::UploadedFile.new("#{Rails.root}/spec/fixtures/files/steelbrickbamboo.jpg", "image/jpeg")]
    f.privacy ProjectPrivacy::PUBLIC
  end
end

#Why: Projects accept nested attributes for images now (excerpt from project.rb):

  has_many :images, :class_name => "ProjectImage", :as => :attachable
  accepts_nested_attributes_for :images, :reject_if => :all_blank, :allow_destroy => true

#Former Factory:

FactoryGirl.define do
  factory :project do |f|
    f.status "Completed"
    f.title {Randgen.word}
    f.brand {FactoryGirl.create :designer}
    f.body {Randgen.sentence}
    f.user {FactoryGirl.create(:user)}
    f.project_image { Rack::Test::UploadedFile.new("#{Rails.root}/spec/fixtures/files/steelbrickbamboo.jpg", "image/jpeg")}
    f.privacy ProjectPrivacy::PUBLIC
  end
end