Pointer for Ruby array

pointer.rb

class Pointer
  attr_reader :count, :array, :current, :index

  def initialize(array)
    raise unless array.is_a?(Array)
    @array = array.clone
    @count = @array.count
    @current = @array.first
    @index = 0
  end

  def next
    return nil if @index >= @count
    @index += 1
    @current = @array[@index]
  end

  def reset
    @index = 0
    @current = @array[0]
  end


  def inspect
    "#<Pointer array=#{@array.inspect} current=#{@current}>"
  end

  alias :value :current
end

pointer_spec.rb

RSpec.describe Pointer do
  describe '.initialize' do
    it 'should initialize a pointer' do
      array = [1,2,3,4,5]
      pointer = Pointer.new(array)
      expect(pointer.current).to eq 1
      expect(pointer.count).to eq 5
      expect(pointer.index).to eq 0
    end

    it { expect {Pointer.new('test')}.to raise_error }
  end

  describe '.next' do
    it 'should move pointer to next' do
      array = [1,2,3]
      pointer = Pointer.new(array)
      expect(pointer.current).to eq 1
      expect(pointer.next).to eq 2
      expect(pointer.current).to eq 2
      expect(pointer.next).to eq 3
      expect(pointer.current).to eq 3
      expect(pointer.next).to eq nil
      expect(pointer.current).to eq nil
      expect(pointer.next).to eq nil
      expect(pointer.current).to eq nil
      expect(pointer.index).to eq 3
    end
  end
end