Test stickers

gistfile1.rb

 @image_generator.put_campaign_sticker "public/images/stickers/campaign.png"
                                                               
 new_photo                = @image_generator.photo.file_path.sub(/\./, "-sticker.")
 expected_photo           = File.join(Rails.root, 'spec', 'assets', 'test-result-campaign.png')

 new_image = Magick::Image.read(new_photo)[0]
 expected_image = Magick::Image.read(expected_photo)[0]

 new_image.signature.should eql expected_image.signature