css_diff.rb

branches = %w[ master switch-to-sassc ]
tmp = Pathname.new(Dir.tmpdir)

branches.each do |branch|
  asset_dir = tmp + "assets_#{branch}"
  if asset_dir.exist?
    puts "#{asset_dir} exists, skipping"
    next
  end

  FileUtils.rm_rf Rails.root + "tmp/cache"
  FileUtils.rm_rf Rails.root + "public/assets"

  print "precompiling #{branch}... "
  puts(Benchmark.realtime {
  system "git checkout #{branch} && rake assets:precompile", out: IO::NULL, err: IO::NULL
  })

  FileUtils.mv (Rails.root + "public/assets"), asset_dir
end

first, second = *branches.map { |branch|
  Dir[tmp + "assets_#{branch}" + "**" + "*.css"].sort
}

first.zip(second).each do |file1, file2|
  puts "diffing:"
  puts file1
  puts file2

  # Remove lines of just whitespace
  #[file1, file2].each { |file| `sed -i "/^\s*$/d" #{file}` }
  # Remove comments
  #[file1, file2].each { |file| `sed -i "|^/\*|d" #{file}` }

  css_diff = `css-diff #{file1} #{file2}`
  if css_diff.strip == "true"
    puts `diff --text --ignore-space-change --report-identical-files #{file1} #{file2}`
  else
    puts "Files are syntactically identical."
  end
  puts
end