i don't really understand gemspecs, i hope this works

Gemfile

@@ -6,4 +6,5 @@ gem 'appraisal'
 gem 'bump'
 gem 'rake'
 gem 'rspec', '~>2'
-gem 'sqlite3'
+gem 'sqlite3'
+gem 'railties'

Gemfile.lock

@@ -3,14 +3,10 @@ PATH
   specs:
     ar_after_transaction (0.3.0)
       activerecord
-      rails
 
 GEM
   remote: https://rubygems.org/
   specs:
-    actionmailer (3.2.13)
-      actionpack (= 3.2.13)
-      mail (~> 2.5.3)
     actionpack (3.2.13)
       activemodel (= 3.2.13)
       activesupport (= 3.2.13)
@@ -29,9 +25,6 @@ GEM
       activesupport (= 3.2.13)
       arel (~> 3.0.2)
       tzinfo (~> 0.3.29)
-    activeresource (3.2.13)
-      activemodel (= 3.2.13)
-      activesupport (= 3.2.13)
     activesupport (3.2.13)
       i18n (= 0.6.1)
       multi_json (~> 1.0)
@@ -47,27 +40,14 @@ GEM
     i18n (0.6.1)
     journey (1.0.4)
     json (1.8.0)
-    mail (2.5.4)
-      mime-types (~> 1.16)
-      treetop (~> 1.4.8)
-    mime-types (1.23)
-    multi_json (1.7.6)
-    polyglot (0.3.3)
+    multi_json (1.7.7)
     rack (1.4.5)
     rack-cache (1.2)
       rack (>= 0.4)
     rack-ssl (1.3.3)
       rack
     rack-test (0.6.2)
       rack (>= 1.0)
-    rails (3.2.13)
-      actionmailer (= 3.2.13)
-      actionpack (= 3.2.13)
-      activerecord (= 3.2.13)
-      activeresource (= 3.2.13)
-      activesupport (= 3.2.13)
-      bundler (~> 1.0)
-      railties (= 3.2.13)
     railties (3.2.13)
       actionpack (= 3.2.13)
       activesupport (= 3.2.13)
@@ -94,9 +74,6 @@ GEM
     sqlite3 (1.3.6)
     thor (0.18.1)
     tilt (1.4.1)
-    treetop (1.4.12)
-      polyglot
-      polyglot (>= 0.3.1)
     tzinfo (0.3.37)
 
 PLATFORMS
@@ -106,6 +83,7 @@ DEPENDENCIES
   appraisal
   ar_after_transaction!
   bump
+  railties
   rake
   rspec (~> 2)
   sqlite3

ar_after_transaction.gemspec

@@ -8,6 +8,5 @@ Gem::Specification.new "ar_after_transaction", ARAfterTransaction::VERSION do |s
   s.homepage = "http://github.com/grosser/ar_after_transaction"
   s.files = `git ls-files`.split("\n")
   s.add_runtime_dependency "activerecord"
-  s.add_runtime_dependency "rails"
   s.license = "MIT"
 end

gemfiles/rails2.gemfile.lock

@@ -3,34 +3,18 @@ PATH
   specs:
     ar_after_transaction (0.3.0)
       activerecord
-      rails
 
 GEM
   remote: https://rubygems.org/
   specs:
-    actionmailer (2.3.14)
-      actionpack (= 2.3.14)
-    actionpack (2.3.14)
-      activesupport (= 2.3.14)
-      rack (~> 1.1.0)
     activerecord (2.3.14)
       activesupport (= 2.3.14)
-    activeresource (2.3.14)
-      activesupport (= 2.3.14)
     activesupport (2.3.14)
     appraisal (0.4.1)
       bundler
       rake
     bump (0.3.5)
     diff-lcs (1.1.3)
-    rack (1.1.6)
-    rails (2.3.14)
-      actionmailer (= 2.3.14)
-      actionpack (= 2.3.14)
-      activerecord (= 2.3.14)
-      activeresource (= 2.3.14)
-      activesupport (= 2.3.14)
-      rake (>= 0.8.3)
     rake (0.9.2.2)
     rspec (2.11.0)
       rspec-core (~> 2.11.0)

gemfiles/rails3.gemfile

@@ -8,6 +8,6 @@ gem "rake"
 gem "rspec", "~>2"
 gem "sqlite3"
 gem "activerecord", "~>3.2.7"
-gem "railties", '~> 3.2.7'
+gem "railties", "~>3.2.7"
 
 gemspec :path=>"../"

gemfiles/rails3.gemfile.lock

@@ -3,14 +3,10 @@ PATH
   specs:
     ar_after_transaction (0.3.0)
       activerecord
-      rails
 
 GEM
   remote: https://rubygems.org/
   specs:
-    actionmailer (3.2.8)
-      actionpack (= 3.2.8)
-      mail (~> 2.4.4)
     actionpack (3.2.8)
       activemodel (= 3.2.8)
       activesupport (= 3.2.8)
@@ -29,9 +25,6 @@ GEM
       activesupport (= 3.2.8)
       arel (~> 3.0.2)
       tzinfo (~> 0.3.29)
-    activeresource (3.2.8)
-      activemodel (= 3.2.8)
-      activesupport (= 3.2.8)
     activesupport (3.2.8)
       i18n (~> 0.6)
       multi_json (~> 1.0)
@@ -47,28 +40,14 @@ GEM
     i18n (0.6.1)
     journey (1.0.4)
     json (1.8.0)
-    mail (2.4.4)
-      i18n (>= 0.4.0)
-      mime-types (~> 1.16)
-      treetop (~> 1.4.8)
-    mime-types (1.23)
     multi_json (1.3.6)
-    polyglot (0.3.3)
     rack (1.4.5)
     rack-cache (1.2)
       rack (>= 0.4)
     rack-ssl (1.3.3)
       rack
     rack-test (0.6.2)
       rack (>= 1.0)
-    rails (3.2.8)
-      actionmailer (= 3.2.8)
-      actionpack (= 3.2.8)
-      activerecord (= 3.2.8)
-      activeresource (= 3.2.8)
-      activesupport (= 3.2.8)
-      bundler (~> 1.0)
-      railties (= 3.2.8)
     railties (3.2.8)
       actionpack (= 3.2.8)
       activesupport (= 3.2.8)
@@ -94,9 +73,6 @@ GEM
     sqlite3 (1.3.6)
     thor (0.18.1)
     tilt (1.4.1)
-    treetop (1.4.14)
-      polyglot
-      polyglot (>= 0.3.1)
     tzinfo (0.3.33)
 
 PLATFORMS

spec/after_initialize_spec.rb

@@ -1,8 +1,17 @@
-require 'rails'
 require 'active_record'
 require File.expand_path '../setup_database', __FILE__
 
-if Rails::VERSION::MAJOR >= 3
+railtie = false
+
+begin
+  require 'action_controller/railtie'
+  railtie = true
+rescue LoadError
+  puts 'Railtie not loaded, skipping test'
+end
+
+if railtie
+
   module Passthrough
     def self.extended( base )
       base.class_eval do