Ruby Image Blur exercise

blur.rb

require 'test/unit'

# complete for YouTube video.

class Image
  attr_accessor :outer_array, :new_outer_array

  def initialize(*arr)
    @outer_array = arr
  end

  def output_image(second_dimensional_array)
    second_dimensional_array.each do |inner_array|
      inner_array.each do |individual_element|
        print individual_element
      end
      puts ""
    end
  end

  def blur
    outer_array_max_length = @outer_array.length
    # 0 indexing.  length though starts at 1.  Which means it will be length of five, but end at arr[4].
    # Unfortunately, requires a deep copy to make this work.
    @new_outer_array = Marshal.load( Marshal.dump(@outer_array) )
    array_checker = []
    @outer_array.each_with_index do |inner_array, outer_arr_index|
      prev_outer_index = outer_arr_index - 1
      next_outer_index = outer_arr_index + 1
      inner_array.each_with_index do |individual_element, inner_arr_index|
        inner_array_max_length = inner_array.length
        prev_inner_index = inner_arr_index - 1
        next_inner_index = inner_arr_index + 1
        # Store the ability to mutate a future number so it does not run it before reaching that point.
        if individual_element == 1
          if prev_outer_index >= 0
            @new_outer_array[prev_outer_index][inner_arr_index] = 1
          end
          if next_outer_index < outer_array_max_length
            # TODO:  You can't run this yet because it will potentially mutate further down the line.
            # array_checker.push([next_outer_index, inner_arr_index])
            @new_outer_array[next_outer_index][inner_arr_index] = 1
          end
          if prev_inner_index >= 0
            @new_outer_array[outer_arr_index][prev_inner_index] = 1
          end
          if next_inner_index < inner_array_max_length
            # TODO:  You can't run this yet because it will potentially mutate further down the line.
            # array_checker.push([outer_arr_index, next_inner_index])
            @new_outer_array[outer_arr_index][next_inner_index] = 1
          end
        end
        if array_checker.index([outer_arr_index, inner_arr_index]) != nil
          @new_outer_array[outer_arr_index][inner_arr_index] = 1
        end
      end
    end
  end
end

# Red, green, refactor.

class BLUR_TEST < Test::Unit::TestCase

  def test_blur_will_change_values_to_ones_in_adjacent_places
    test_arr = [
        [0, 0, 1, 0],
        [0, 0, 0, 0],
        [0, 1, 0, 1]
    ]
    image = Image.new(
       test_arr[0],
       test_arr[1],
       test_arr[2]
    )

    assert(image.outer_array == test_arr, 'test array and image array do not match')

    blurred_array_expectation = [
        [0, 1, 1, 1],
        [0, 1, 1, 1],
        [1, 1, 1, 1]
    ]
    image.blur
    blurred_array_actual = image.new_outer_array
    assert(blurred_array_expectation == blurred_array_actual, 'blurring failed')
  end

end