3 files changed, 12 insertions, 4 deletions
diff --git a/activesupport/lib/active_support/testing/isolation.rb b/activesupport/lib/active_support/testing/isolation.rb
index 8f7d1c29a9..c75b59c284 100644
--- a/activesupport/lib/active_support/testing/isolation.rb
+++ b/activesupport/lib/active_support/testing/isolation.rb
@@ -1,5 +1,3 @@
-require "active_support/core_ext/load_error"
-
 module ActiveSupport
   module Testing
     class ProxyTestResult
diff --git a/activesupport/lib/active_support/vendor.rb b/activesupport/lib/active_support/vendor.rb
index 9f464c8246..0f9b0c7554 100644
--- a/activesupport/lib/active_support/vendor.rb
+++ b/activesupport/lib/active_support/vendor.rb
@@ -1,3 +1,5 @@
+require 'pathname'
+
 def ActiveSupport.requirable?(file)
   $LOAD_PATH.any? { |p| Dir.glob("#{p}/#{file}.*").any? }
 end
@@ -10,7 +12,8 @@ end
       gem lib, "~> #{version}"
       # Use the vendored lib if the gem's missing or we aren't using RubyGems.
     rescue LoadError, NoMethodError
-      $LOAD_PATH.unshift File.expand_path("#{File.dirname(__FILE__)}/vendor/#{lib}-#{version}/lib")
+      # There could be symlinks
+      $LOAD_PATH.unshift Pathname.new(__FILE__).dirname.join("vendor/#{lib}-#{version}/lib").realpath.to_s
     end
   end
 end
diff --git a/activesupport/test/abstract_unit.rb b/activesupport/test/abstract_unit.rb
index af9656615c..f390c66838 100644
--- a/activesupport/test/abstract_unit.rb
+++ b/activesupport/test/abstract_unit.rb
@@ -1,4 +1,12 @@
 ORIG_ARGV = ARGV.dup
+root = File.expand_path('../../..', __FILE__)
+begin
+  require "#{root}/vendor/gems/environment"
+rescue LoadError
+  $:.unshift("#{root}/activesupport/lib")
+  $:.unshift("#{root}/activerecord/lib")
+end
+
 
 require 'test/unit'
 
@@ -11,7 +19,6 @@ rescue LoadError
 end
 
 ENV['NO_RELOAD'] = '1'
-$:.unshift "#{File.dirname(__FILE__)}/../lib"
 require 'active_support'
 require 'active_support/test_case'