A RSpec test that checks all your images for proper compression

image_spec.rb

require "spec_helper"
require 'fastimage'

describe "Image Compression" do

  Dir[Rails.root.join("app/assets/images/*.{jpg,png,gif}")].each do |file|
    context "#{file}" do
      it "should be properly dimensioned" do
        FastImage.size(file).each do |dim|
          dim.should < 2000 # pixels
        end
      end

      it "should be properly sized" do
        File.size(file).should < 358400 #350kb
      end

      it "should be properly compressed" do
        pixels = FastImage.size(file).inject(:*)
        if pixels > 1000
          size = File.size(file)
          (size.to_f/pixels.to_f).should < 2.5 #bytes/pixels ratio
        end
      end

    end
  end

end