`url_for` does not modify polymorphic options

The `url_for` methods in `actionpack` and `actionview`
now make a copy of the provided options
before generating polymorphic paths or URLs.

The bug in the previous behavior
is most noticeable in a case like:

    url_options = [:new, :post, param: 'value']

    if current_page?(url_options)
      css_class = "active"
    end

    link_to "New Post", url_options, class: css_class

1 files changed, 14 insertions, 0 deletions

diff --git a/actionview/test/template/url_helper_test.rb b/actionview/test/template/url_helper_test.rb
index 027b72b354..50b7865f88 100644
--- a/actionview/test/template/url_helper_test.rb
+++ b/actionview/test/template/url_helper_test.rb
@@ -785,6 +785,13 @@ class SessionsController < ActionController::Base
     @session = Session.new(params[:id])
     render inline: "<%= url_for([@workshop, @session]) %>\n<%= link_to('Session', [@workshop, @session]) %>"
   end
+
+  def edit
+    @workshop = Workshop.new(params[:workshop_id])
+    @session = Session.new(params[:id])
+    @url = [@workshop, @session, format: params[:format]]
+    render inline: "<%= url_for(@url) %>\n<%= link_to('Session', @url) %>"
+  end
 end
 
 class PolymorphicControllerTest < ActionController::TestCase
@@ -815,4 +822,11 @@ class PolymorphicControllerTest < ActionController::TestCase
     get :show, params: { workshop_id: 1, id: 1 }
     assert_equal %{/workshops/1/sessions/1\n<a href="/workshops/1/sessions/1">Session</a>}, @response.body
   end
+
+  def test_existing_nested_resource_with_params
+    @controller = SessionsController.new
+
+    get :edit, params: { workshop_id: 1, id: 1, format: "json"  }
+    assert_equal %{/workshops/1/sessions/1.json\n<a href="/workshops/1/sessions/1.json">Session</a>}, @response.body
+  end
 end