module TimeExtensions
  %w[ round floor ceil ].each do |_method|
    define_method _method do |*args|
      seconds = args.first || 60
      Time.at((self.to_f / seconds).send(_method) * seconds)
    end
  end

  def end_of_minute
    change(:sec => 59, :usec => 999999.999)
  end

  def beginning_of_minute
    change(:sec => 0, :usec => 0)
  end
end

Time.send :include, TimeExtensions