lib/fakefs/pathname.rb
def join(*args)
      args.unshift self
      result = args.pop
      result = Pathname.new(result) unless result.is_a?(Pathname)
      return result if result.absolute?
      args.reverse_each do |arg|
        arg = Pathname.new(arg) unless arg.is_a?(Pathname)
        result = arg + result
        return result if result.absolute?
      end
      result
    end
def join(*args)
      args.unshift self
      result = args.pop
      result = Pathname.new(result) unless result.is_a?(Pathname)
      return result if result.absolute?
      args.reverse_each do |arg|
        arg = Pathname.new(arg) unless arg.is_a?(Pathname)
        result = arg + result
        return result if result.absolute?
      end
      result
    end
Pathname#join joins pathnames.

 <tt>path0.join(path1, ..., pathN)</tt> is the same as
 <tt>path0 + path1 + ... + pathN</tt>.