Delegate CollectionDecorator#== to decorated collection

Decorator#== compares sources, so CollectionDecorator#== can just
use a standard array comparison with the decorated collection.

This covers the case that the decorated and source collections
differ because of changes made after decoration.

lib/draper/collection_decorator.rb

@@ -6,7 +6,7 @@ module Draper
     attr_accessor :context
 
     array_methods = Array.instance_methods - Object.instance_methods
-    delegate :as_json, *array_methods, to: :decorated_collection
+    delegate :==, :as_json, *array_methods, to: :decorated_collection
 
     # @param source collection to decorate
     # @option options [Class] :with the class used to decorate items
@@ -34,10 +34,6 @@ module Draper
       end
     end
 
-    def ==(other)
-      source == (other.respond_to?(:source) ? other.source : other)
-    end
-
     def to_s
       klass = begin
         decorator_class

spec/draper/collection_decorator_spec.rb

@@ -228,6 +228,16 @@ describe Draper::CollectionDecorator do
         a.should_not == b
       end
     end
+
+    context "when the decorated collection has been modified" do
+      it "is no longer equal to the source" do
+        a = Draper::CollectionDecorator.new(source, with: ProductDecorator)
+        b = source.dup
+
+        a << Product.new.decorate
+        a.should_not == b
+      end
+    end
   end
 
   describe "#to_s" do

spec/draper/decorated_association_spec.rb

@@ -86,7 +86,7 @@ describe Draper::DecoratedAssociation do
       let(:options) { {scope: :foo} }
 
       it "applies the scope before decoration" do
-        scoped = [:scoped]
+        scoped = [Product.new]
         associated.should_receive(:foo).and_return(scoped)
         decorated_association.call.should == scoped
       end