diff options
| -rw-r--r-- | activemodel/lib/active_model/observing.rb | 11 | ||||
| -rw-r--r-- | activemodel/test/cases/observing_test.rb | 15 |
2 files changed, 21 insertions, 5 deletions
diff --git a/activemodel/lib/active_model/observing.rb b/activemodel/lib/active_model/observing.rb index 35b1a1f0c7..cc60c9ac72 100644 --- a/activemodel/lib/active_model/observing.rb +++ b/activemodel/lib/active_model/observing.rb @@ -90,14 +90,15 @@ module ActiveModel def instantiate_observer(observer) #:nodoc: # string/symbol if observer.respond_to?(:to_sym) - observer.to_s.camelize.constantize.instance - elsif observer.respond_to?(:instance) + observer = observer.to_s.camelize.constantize + end + if observer.respond_to?(:instance) observer.instance else raise ArgumentError, - "#{observer} must be a lowercase, underscored class name (or an " + - "instance of the class itself) responding to the instance " + - "method. Example: Person.observers = :big_brother # calls " + + "#{observer} must be a lowercase, underscored class name (or " + + "the class itself) responding to the method :instance. " + + "Example: Person.observers = :big_brother # calls " + "BigBrother.instance" end end diff --git a/activemodel/test/cases/observing_test.rb b/activemodel/test/cases/observing_test.rb index df070d2d8e..1a80b5d854 100644 --- a/activemodel/test/cases/observing_test.rb +++ b/activemodel/test/cases/observing_test.rb @@ -70,6 +70,21 @@ class ObservingTest < ActiveModel::TestCase ObservedModel.instantiate_observers end + test "raises an appropriate error when a developer accidentally adds the wrong class (i.e. Widget instead of WidgetObserver)" do + assert_raise ArgumentError do + ObservedModel.observers = ['string'] + ObservedModel.instantiate_observers + end + assert_raise ArgumentError do + ObservedModel.observers = [:string] + ObservedModel.instantiate_observers + end + assert_raise ArgumentError do + ObservedModel.observers = [String] + ObservedModel.instantiate_observers + end + end + test "passes observers to subclasses" do FooObserver.instance bar = Class.new(Foo) |