find-missing-lib.rb

#!/usr/bin/ruby
require 'set'
lib = Set.new

ARGV.each do |dir|
  Dir.glob("#{dir}/**/*.rb").each do |rb|
    File.foreach(rb) do |line|
      if line =~ /^\s*require\s+["'](.*?)["']\s*$/
        lib_str = $1
        break if lib_str[0, 8] == "bundler/" # Skip file using bundler.
        lib.add lib_str
      end
    end
  end
end

lib.each do |l|
  begin
    require l
  rescue
    puts l
  end
end