Fix bug with AM::Observer disablement.

Now that we propagate the enabling/disabling to descendants, we no longer have to check the disabled_observer Set on each superclass of the model class.  This was causing a bug when disabling all observers at a superclass level and then enabling an individual observer at a subclass level.

Plus the logic is simpler now :).

3 files changed, 27 insertions, 25 deletions

diff --git a/activemodel/lib/active_model/observer_array.rb b/activemodel/lib/active_model/observer_array.rb
index d501215dd6..ab7f86007f 100644
--- a/activemodel/lib/active_model/observer_array.rb
+++ b/activemodel/lib/active_model/observer_array.rb
@@ -4,34 +4,16 @@ module ActiveModel
   # Stores the enabled/disabled state of individual observers for
   # a particular model classes.
   class ObserverArray < Array
-    # returns false if:
-    #   - the ObserverArray for the given model's class has the given observer
-    #     in its disabled_observers set.
-    #   - or that is the case at any level of the model's superclass chain.
-    def self.observer_enabled?(observer, model)
-      klass = model.class
-      observer_class = observer.class
-
-      loop do
-        break unless klass.respond_to?(:observers)
-        array = klass.observers
-        return false if array.disabled_observers.include?(observer_class)
-        klass = klass.superclass
-      end
-
-      true # observers are enabled by default
-    end
-
-    def disabled_observers
-      @disabled_observers ||= Set.new
-    end
-
     attr_reader :model_class
     def initialize(model_class, *args)
       @model_class = model_class
       super(*args)
     end
 
+    def disabled_for?(observer)
+      disabled_observers.include?(observer.class)
+    end
+
     def disable(*observers, &block)
       set_enablement(false, observers, &block)
     end
@@ -42,6 +24,10 @@ module ActiveModel
 
     protected
 
+      def disabled_observers
+        @disabled_observers ||= Set.new
+      end
+
       def observer_class_for(observer)
         return observer if observer.is_a?(Class)
 
diff --git a/activemodel/lib/active_model/observing.rb b/activemodel/lib/active_model/observing.rb
index 9ffcda8dd7..c1ac4eb4af 100644
--- a/activemodel/lib/active_model/observing.rb
+++ b/activemodel/lib/active_model/observing.rb
@@ -222,9 +222,9 @@ module ActiveModel
 
     # Send observed_method(object) if the method exists.
     def update(observed_method, object) #:nodoc:
-      if respond_to?(observed_method) && ObserverArray.observer_enabled?(self, object)
-        send(observed_method, object)
-      end
+      return unless respond_to?(observed_method)
+      return if disabled_for?(object)
+      send(observed_method, object)
     end
 
     # Special method sent by the observed class when it is inherited.
@@ -238,5 +238,11 @@ module ActiveModel
       def add_observer!(klass) #:nodoc:
         klass.add_observer(self)
       end
+
+      def disabled_for?(object)
+        klass = object.class
+        return false unless klass.respond_to?(:observers)
+        klass.observers.disabled_for?(self)
+      end
   end
 end
diff --git a/activemodel/test/cases/observer_array_test.rb b/activemodel/test/cases/observer_array_test.rb
index 38e4fd59fc..3ede5682b4 100644
--- a/activemodel/test/cases/observer_array_test.rb
+++ b/activemodel/test/cases/observer_array_test.rb
@@ -65,6 +65,16 @@ class ObserverArrayTest < ActiveModel::TestCase
     assert_observer_notified     Budget, AuditTrail
   end
 
+  test "can enable observers on individual models without affecting those observers on other models" do
+    ORM.observers.disable :all
+    Budget.observers.enable AuditTrail
+
+    assert_observer_not_notified Widget, WidgetObserver
+    assert_observer_not_notified Budget, BudgetObserver
+    assert_observer_not_notified Widget, AuditTrail
+    assert_observer_notified     Budget, AuditTrail
+  end
+
   test "can disable observers for the duration of a block" do
     yielded = false
     ORM.observers.disable :budget_observer do