For file uploads in Ruby, the “CarrierWave” gem seems to be convenient.

Since it supports Rack, it works with Rack-based Ruby applications like Rails and Sinatra, and supports many ORMs including ActiveRecord, DataMapper, and Mongoid.

・jnicklas/carrierwave · GitHub

・ASCIIcasts - “Episode 253 - CarrierWaveでファイルのアップロード”

・Railsでcarrierwaveを使って画像ファイルのアップロード

.gitignore

# CarrierWave
/public/uploads

・gist:2874877

When creating test data, you can assign an image to a model in rails c and save it.

photo = Photo.new
photo.image = File.open('app/assets/images/dummy.jpg')

Testing with RSpec

include ActionDispatch::TestProcess

FactoryGirl.define do
  factory :photo do
    ignore do
      image_file "test1.jpg"
    end

    name "TestPhoto"
    image { fixture_file_upload(Rails.root.join('spec', 'support', 'test_images', "#{image_file}"), 'image/jpg') }
  end
end

・Action*3 - rspecでCarrierWaveのアップロードファイルをclean

・How to: Cleanup after your Rspec tests · jnicklas/carrierwave Wiki

That’s all from the Gemba.