class Bundler::Index

def unmet_dependency_names
  dependency_names = specs.values.map do |array_of_s|
    array_of_s.map do |s|
      s.dependencies.map{|d| d.name }
    end
  end.flatten.uniq
  dependency_names.select{|name| name != 'bundler' && specs_by_name(name).empty? }
end