Merge pull request #25912 from stevenharman/fix_render_partial_collection_to_allow_custom_collection

Changed partial rendering to allow collections which don't implement `#to_ary`.

actionview/CHANGELOG.md

@@ -1,5 +1,16 @@
 ## Rails 5.0.0 (June 30, 2016) ##
 
+*   Changed partial rendering with a collection to allow collections which
+    implement `to_a`.
+
+    Extracting the collection option had an optimization to avoid unnecessary
+    queries of ActiveRecord Relations by calling `#to_ary` on the given
+    collection. Instances of `Enumerator` or `Enumerable` are valid
+    collections, but they do not implement `#to_ary`. By changing this to
+    `#to_a`, they will now be extracted and rendered as expected.
+
+    *Steven Harman*
+
 *   Change `datetime_field` and `datetime_field_tag` to generate `datetime-local` fields.
 
     As a new specification of the HTML 5 the text field type `datetime` will no longer exist

actionview/lib/action_view/renderer/partial_renderer.rb

@@ -403,7 +403,7 @@ module ActionView
     def collection_from_options
       if @options.key?(:collection)
         collection = @options[:collection]
-        collection.respond_to?(:to_ary) ? collection.to_ary : []
+        collection ? collection.to_a : []
       end
     end
 

actionview/test/template/render_test.rb

@@ -309,6 +309,14 @@ module RenderTestCases
     assert_nil @view.render(:partial => "test/customer", :collection => nil)
   end
 
+  def test_render_partial_collection_for_non_array
+    customers = Enumerator.new do |y|
+      y.yield(Customer.new("david"))
+      y.yield(Customer.new("mary"))
+    end
+    assert_equal "Hello: davidHello: mary", @view.render(partial: "test/customer", collection: customers)
+  end
+
   def test_render_partial_without_object_does_not_put_partial_name_to_local_assigns
     assert_equal 'false', @view.render(partial: 'test/partial_name_in_local_assigns')
   end