module Devise::Models::Validatable

def self.assert_validations_api!(base) #:nodoc:
  unavailable_validations = VALIDATIONS.select { |v| !base.respond_to?(v) }
  unless unavailable_validations.empty?
    raise "Could not use :validatable module since #{base} does not respond " <<
          "to the following methods: #{unavailable_validations.to_sentence}."
  end
end