Merge pull request #2065 from elight/3-1-stable

Backport of cache_key fix from master

activerecord/lib/active_record/base.rb

@@ -1639,7 +1639,8 @@ MSG
         when new_record?
           "#{self.class.model_name.cache_key}/new"
         when timestamp = self[:updated_at]
-          "#{self.class.model_name.cache_key}/#{id}-#{timestamp.to_s(:number)}"
+          timestamp = timestamp.utc.to_s(:number)
+          "#{self.class.model_name.cache_key}/#{id}-#{timestamp}"
         else
           "#{self.class.model_name.cache_key}/#{id}"
         end

activerecord/test/cases/base_test.rb

@@ -478,11 +478,11 @@ class BasicsTest < ActiveRecord::TestCase
   def test_hashing
     assert_equal [ Topic.find(1) ], [ Topic.find(2).topic ] & [ Topic.find(1) ]
   end
-  
+
   def test_comparison
     topic_1 = Topic.create!
     topic_2 = Topic.create!
-    
+
     assert_equal [topic_2, topic_1].sort, [topic_1, topic_2]
   end
 
@@ -1832,4 +1832,29 @@ class BasicsTest < ActiveRecord::TestCase
   def test_attribtue_names_on_abstract_class
     assert_equal [], AbstractCompany.attribute_names
   end
+
+  def test_cache_key_for_existing_record_is_not_timezone_dependent
+    ActiveRecord::Base.time_zone_aware_attributes = true
+
+    Time.zone = "UTC"
+    utc_key = Developer.first.cache_key
+
+    Time.zone = "EST"
+    est_key = Developer.first.cache_key
+
+    assert_equal utc_key, est_key
+  ensure
+    ActiveRecord::Base.time_zone_aware_attributes = false
+  end
+
+  def test_cache_key_format_for_existing_record_with_updated_at
+    dev = Developer.first
+    assert_equal "developers/#{dev.id}-#{dev.updated_at.utc.to_s(:number)}", dev.cache_key
+  end
+
+  def test_cache_key_format_for_existing_record_with_nil_updated_at
+    dev = Developer.first
+    dev.update_attribute(:updated_at, nil)
+    assert_match /\/#{dev.id}$/, dev.cache_key
+  end
 end