Evented notifications take priority over Timed notifications

In cases where a notification subscriber includes methods to support
both Evented and Timed events, Evented should take priority over Timed.
This allows subscribers to be backwards compatible (older Rails only
allows Timed events) while defaulting to newer behavior.

2 files changed, 23 insertions, 3 deletions

diff --git a/activesupport/lib/active_support/notifications/fanout.rb b/activesupport/lib/active_support/notifications/fanout.rb
index 6ffc091233..2e5bcf4639 100644
--- a/activesupport/lib/active_support/notifications/fanout.rb
+++ b/activesupport/lib/active_support/notifications/fanout.rb
@@ -59,10 +59,10 @@ module ActiveSupport
 
       module Subscribers # :nodoc:
         def self.new(pattern, listener)
-          if listener.respond_to?(:call)
-            subscriber = Timed.new pattern, listener
-          else
+          if listener.respond_to?(:start) and listener.respond_to?(:finish)
             subscriber = Evented.new pattern, listener
+          else
+            subscriber = Timed.new pattern, listener
           end
 
           unless pattern
diff --git a/activesupport/test/notifications/evented_notification_test.rb b/activesupport/test/notifications/evented_notification_test.rb
index f77a0eb3fa..f690ad43fc 100644
--- a/activesupport/test/notifications/evented_notification_test.rb
+++ b/activesupport/test/notifications/evented_notification_test.rb
@@ -19,6 +19,12 @@ module ActiveSupport
         end
       end
 
+      class ListenerWithTimedSupport < Listener
+        def call(name, start, finish, id, payload)
+          @events << [:call, name, start, finish, id, payload]
+        end
+      end
+
       def test_evented_listener
         notifier = Fanout.new
         listener = Listener.new
@@ -62,6 +68,20 @@ module ActiveSupport
           [:finish,  'hello', 1, {}],
         ], listener.events
       end
+
+      def test_evented_listener_priority
+        notifier = Fanout.new
+        listener = ListenerWithTimedSupport.new
+        notifier.subscribe 'hi', listener
+
+        notifier.start 'hi', 1, {}
+        notifier.finish 'hi', 1, {}
+
+        assert_equal [
+          [:start, 'hi', 1, {}],
+          [:finish, 'hi', 1, {}]
+        ], listener.events
+      end
     end
   end
 end