mega_loto.rb

#This could work:
class MegaLotto
  NUMBERS = 5

  def self.draw
    NUMBERS.times.inject([]) do |arr, i|
      arr << self.random_draw
    end
  end

  private

  def self.random_draw
    rand(0...60)
  end
end

LotteryDrawing.draw


#However I don't like the inject method, because it is needles here, constant and private ... IMHO it would look much better:

require 'minitest/autorun'

class MegaLotto

  def draw(number_of_results: 5, range: 0...60)
    number_of_results.times.collect { random_draw(range) }
  end

  def random_draw(range)
    rand(range)
  end
end

class TestMegaLotto < MiniTest::Test

  def setup
    @mega_loto = MegaLotto.new
    @mega_loto_draw = @mega_loto.draw
  end

  def test_implements_draw_and_random_draw
    assert_respond_to @mega_loto, :random_draw
    assert_respond_to @mega_loto, :draw
  end

  def test_draw_is_array
    assert_kind_of Array, @mega_loto_draw
  end

  def test_draw_is_random
    refute_equal MegaLotto.new.draw, @mega_loto_draw
  end
end

#Or maybe: 

require 'minitest/autorun'

class MegaLotto

  def draw(number_of_results: 5, range: 0...60)
    range.to_a.sample(number_of_results)
  end

end

class TestMegaLotto < MiniTest::Test

  def setup
    @mega_loto = MegaLotto.new
    @mega_loto_draw = @mega_loto.draw
  end

  def test_implements_draw
    assert_respond_to @mega_loto, :draw
  end

  def test_draw_is_array
    assert_kind_of Array, @mega_loto_draw
  end

  def test_draw_is_random
    refute_equal MegaLotto.new.draw, @mega_loto_draw
  end
end