RPN w one test not passing

RPN - almost complete

class RPNCalculator
  
  attr_accessor :calculator, :result, :subtotal, :mini_array
  
  def initialize
    @calculator = []
    @mini_array = []
    @result = 0
    @subtotal = 0
  end
  
  def push(arg)
    @calculator << arg
  end
  
  def plus
      if @calculator.length > 2
        @mini_array = @calculator.pop 2
          @mini_array.each do |i|
            @subtotal += i
          end
        @result = @subtotal
        @calculator.push @subtotal
      else
        @mini_array = @calculator.pop 2
        @subtotal = (@mini_array[0] + @mini_array[1])
        @calculator.push @subtotal
        @result = @calculator[0]
      end
  end
   
  def minus
    if @calculator.length > 2
      @mini_array = @calculator.pop 2
      @subtotal = @mini_array[-2] - @mini_array[-1]
      @result = @subtotal
      @calculator.push @subtotal
    else
      @calculator.push(@calculator[-2] - @calculator[-1])
      @result = @calculator[-1]
      end
    end     
    
  def times
    if @calculator.length > 2
      @mini_array = @calculator.pop 2
      @subtotal = @mini_array[0] * @mini_array[1]
      @result = @subtotal
      @calculator.push @subtotal
    else
      @mini_array = @calculator.pop 2
      @subtotal = @mini_array[0] * @mini_array[1]
      @calculator.push @subtotal
      @result = @subtotal
      end
  end 
  
  def divide
    if @calculator.length > 2
      @mini_array = @calculator.pop 2
      @subtotal = @mini_array[-2].to_f / @mini_array[-1]
      @result = @subtotal
      @calculator.push @subtotal
    else
      @calculator.push(@calculator[-2].to_f / @calculator[-1])
      @result = @calculator[-1]
      end
  end
  
  def value
    @result
  end

end