class Jeweler::Commands::CheckDependencies

def find_missing_dependencies
  if Gem::Specification.respond_to?(:find_by_name)
    dependencies.select do |dependency|
      begin
        spec = Gem::Specification.find_by_name(dependency.name, *dependency.requirement.as_list)
        spec.activate if spec
        !spec
      rescue LoadError => e
        true
      end
    end
  else
    dependencies.select do |dependency|
      begin
        Gem.activate dependency.name, *dependency.requirement.as_list
        false
      rescue LoadError => e
        true
      end
    end
  end
end