Write some code, that will flatten an array of arbitrarily nested arrays of integers into a flat array of integers

flatten.rb

class Flatten
  def self.flatten input, answer = []
    # Function is called recursively if element of input is an Array.
    # If element is not an Array, it is pushed to answer.
    input.each do |element|
      element.is_a?(Array) ? self.flatten(element, answer) : answer << element
    end
    answer
  end
end

flatten_test.rb

require 'minitest/autorun'
require_relative 'flatten'

class FlattenTest < Minitest::Test
  def test_flatten_simple
    assert_equal [1,2,3,4], Flatten.flatten([[1,2,[3]],4])
  end

  def test_flatten_intermediate
    assert_equal [1,2,3,4], Flatten.flatten([[[[1,[2],[3]],4]]])
  end

  def test_flatten_complex
    assert_equal [1,2,3,4,5,6,7], Flatten.flatten([[[[1,2],3,4,5],6],7])
  end

  def test_flatten_monster
    assert_equal [19,57,1,69,0], Flatten.flatten([[[19],[57]],[[1],[[69],[0]]]])
  end
end

Please reach out to me if you need any clarification about my code: [email protected]