Flatten array in Ruby

flatten.rb

class RecursiveFlattenMethod

  attr_reader :result
  def flatten_nested_arrays(arr, result=[])
    arr.each do |element|
      if element.class != Array
        result << element
      else
        flatten_nested_arrays(element, result)
      end
    end
    result
  end

end

test_flatten.rb

require 'minitest'
require 'minitest/autorun'
require './flatten'

class FlattenTest < Minitest::Test
  def test_flatten_arrays
    bumpy_array = [1, [2, 3, [4, 5]]]
    expected_result = [1, 2, 3, 4, 5]

    assert_equal expected_result, RecursiveFlattenMethod.new.flatten_nested_arrays(bumpy_array)
  end

  def test_flatten_arrays_different_datatypes
    bumpy_array = [1, ["2", "3", [4, 5]]]
    expected_result = [1, "2", "3", 4, 5]

    assert_equal expected_result, RecursiveFlattenMethod.new.flatten_nested_arrays(bumpy_array)
  end

  def test_flatten_arrays_with_array_at_beginning
    bumpy_array = [[1,6], [2, 3, [4, 5]]]
    expected_result = [1, 6, 2, 3, 4, 5]

    assert_equal expected_result, RecursiveFlattenMethod.new.flatten_nested_arrays(bumpy_array)

  end

  def test_flatten_arrays_no_nested
    bumpy_array = [1,6,2,3,4,5]
    expected_result = [1, 6, 2, 3, 4, 5]

    assert_equal expected_result, RecursiveFlattenMethod.new.flatten_nested_arrays(bumpy_array)
  end

  def test_flatten_arrays_multi_unnecessary_nested
    bumpy_array = [[[[[1,2,3,4,5]]]]]
    expected_result = [1, 2, 3, 4, 5]

    assert_equal expected_result, RecursiveFlattenMethod.new.flatten_nested_arrays(bumpy_array)
  end
end