Add hook_rails configuration option to make the Rails extensions optional

lib/sidekiq.rb

@@ -16,6 +16,7 @@ module Sidekiq
     :require => '.',
     :environment => nil,
     :timeout => 5,
+    :hook_rails => true,
   }
 
   def self.options

lib/sidekiq/rails.rb

@@ -1,5 +1,6 @@
 module Sidekiq
   def self.hook_rails!
+    return unless Sidekiq.options[:hook_rails]
     if defined?(ActiveRecord)
       ActiveRecord::Base.extend(Sidekiq::Extensions::ActiveRecord)
       ActiveRecord::Base.send(:include, Sidekiq::Extensions::ActiveRecord)

test/test_extension_configuration.rb

@@ -0,0 +1,28 @@
+require 'helper'
+require 'sidekiq'
+
+class TestExtensionConfiguration < MiniTest::Unit::TestCase
+  describe 'sidekiq rails extensions configuration' do
+    before do
+      @options = Sidekiq.options
+    end
+
+    after do
+      Sidekiq.options = @options
+    end
+    
+    it 'should set hook_rails option to true by default' do
+      assert_equal true, Sidekiq.options[:hook_rails]
+    end
+
+    it 'should extend ActiveRecord and ActiveMailer if hook_rails is true' do
+      assert_equal ActionMailer::Base, Sidekiq.hook_rails!
+    end
+
+    it 'should not extend ActiveRecord and ActiveMailer if hook_rails is false' do
+      Sidekiq.options = { :hook_rails => false }
+      assert_equal nil, Sidekiq.hook_rails!
+    end
+
+  end
+end