use setup block to config which classes to extend

lib/validates_timeliness.rb

@@ -14,6 +14,10 @@ require 'active_support/core_ext/date_time/zones'
 
 module ValidatesTimeliness
 
+  # Add validation helpers to these classes
+  mattr_accessor :extend_classes
+  @@extend_classes = []
+
   # Set the dummy date part for a time type values.
   mattr_accessor :dummy_date_for_time_type
   @@dummy_date_for_time_type = [ 2000, 1, 1 ]
@@ -21,6 +25,12 @@ module ValidatesTimeliness
   # Ignore errors when restriction options are evaluated
   mattr_accessor :ignore_restriction_errors
   @@ignore_restriction_errors = false
+
+  # Setup method for plugin configuration
+  def self.setup
+    yield self
+    extend_classes.each {|klass| klass.send(:include, ValidatesTimeliness::HelperMethods) }
+  end
 end
 
 require 'validates_timeliness/conversion'

lib/validates_timeliness/helper_methods.rb

@@ -1,5 +1,8 @@
 module ValidatesTimeliness
   module HelperMethods
+    extend ActiveSupport::Concern
+
+    module ClassMethods
       def validates_date(*attr_names)
         validates_with Validator, _merge_attributes(attr_names).merge(:type => :date)
       end
@@ -12,8 +15,5 @@ module ValidatesTimeliness
         validates_with Validator, _merge_attributes(attr_names).merge(:type => :datetime)
       end
     end
-end
+  end
-
-module ActiveModel::Validations::HelperMethods
-  include ValidatesTimeliness::HelperMethods
 end

spec/spec_helper.rb

@@ -6,17 +6,15 @@ require 'rspec/autorun'
 
 require 'active_model'
 require 'active_model/validations'
-# require 'active_record'
+require 'active_record'
-# require 'action_controller'
-# require 'action_view'
-# require 'action_mailer'
-# require 'rspec/rails'
-
 require 'timecop'
-require 'model_helpers'
 
 require 'validates_timeliness'
 
+ValidatesTimeliness.setup do |c|
+  c.extend_classes = [ ActiveModel::Validations, ActiveRecord::Base ]
+end
+
 Time.zone = 'Australia/Melbourne'
 
 LOCALE_PATH = File.expand_path(File.dirname(__FILE__) + '/../lib/validates_timeliness/locale/en.yml')
@@ -35,6 +33,8 @@ class Person
   end
 end
 
+require 'model_helpers'
+
 Rspec.configure do |c|
   c.mock_with :rspec
   c.before do