module ActiveModelHelpers
  def custom_validation(options = {}, &block)
    attribute_name = options.fetch(:attribute_name, :attr)
    attribute_type = options.fetch(:attribute_type, :integer)

    define_model(:example, attribute_name => attribute_type) do
      validate :custom_validation

      define_method(:custom_validation, &block)
    end.new
  end
  alias record_with_custom_validation custom_validation

  def validating_format(options)
    define_model :example, attr: :string do
      validates_format_of :attr, options
    end.new
  end
end

RSpec.configure do |c|
  c.include ActiveModelHelpers
end