Delegate constant lookup

article_test.rb

require 'test_helper'

class ArticleTest < ActiveSupport::TestCase
  delegate :validators_on, to: Article

  test "validates presence of title" do
    refute_emtpy validators_on(:title).grep PresenceValidator
  end

private

  def self.const_missing(const)
    return unless const =~ /Validator\z/
    ActiveRecord::Validations.const_get(const)
  end
end