def outdated
    outdateds = []

    latest_specs.each do |local|
      dependency = Gem::Dependency.new local.name, ">= #{local.version}"

      fetcher = Gem::SpecFetcher.fetcher
      remotes = fetcher.find_matching dependency
      remotes = remotes.map { |(_, version, _), _| version }

      latest = remotes.sort.last

      outdateds << local.name if latest and local.version < latest
    end

    outdateds
  end
#
Returns an Array of Gem::Specifications that are not up to date.