snippet.rb

            should "save the files as the right formats and sizes" do
              [[:large, 400, 61, "PNG"],
               [:medium, 100, 15, "GIF"],
               [:small, 32, 32, "JPEG"]].each do |style|
                cmd = %Q[identify -format "%w %h %b %m" "#{@attachment.path(style.first)}"]
                out = `#{cmd}`
                width, height, size, format = out.split(" ")
                assert_equal style[1].to_s, width.to_s
                assert_equal style[2].to_s, height.to_s
                assert_equal style[3].to_s, format.to_s
              end