Decorated collection also responds to decorated_with?

lib/draper/collection_decorator.rb

@@ -66,6 +66,13 @@ module Draper
       true
     end
 
+    # Checks if a given decorator has been applied to the collection.
+    #
+    # @param [Class] decorator_class
+    def decorated_with?(decorator_class)
+      self.instance_of? decorator_class
+    end
+
     def kind_of?(klass)
       decorated_collection.kind_of?(klass) || super
     end

spec/draper/collection_decorator_spec.rb

@@ -243,6 +243,15 @@ module Draper
       end
     end
 
+    describe '#decorated_with?' do
+      it "checks if a decorator has been applied to a collection" do
+        decorator = ProductsDecorator.new([Product.new])
+
+        expect(decorator).to be_decorated_with ProductsDecorator
+        expect(decorator).not_to be_decorated_with OtherDecorator
+      end
+    end
+
     describe '#kind_of?' do
       it 'asks the kind of its decorated collection' do
         decorator = ProductsDecorator.new([])