Use more specific check for :format in route path

The current check for whether to add an optional format to the path
is very lax and will match things like `:format_id` where there are
nested resources, e.g:

    resources :formats do
      resources :items
    end

Fix this by using a more restrictive regex pattern that looks for
the patterns `(.:format)`, `.:format` or `/` at the end of the path.
Note that we need to allow for multiple closing parenthesis since
the route may be of this form:

    get "/books(/:action(.:format))", controller: "books"

This probably isn't what's intended since it means that the default
index action route doesn't support a format but we have a test for
it so we need to allow it.

Fixes #28517.

1 files changed, 18 insertions, 0 deletions

diff --git a/actionpack/test/dispatch/routing_test.rb b/actionpack/test/dispatch/routing_test.rb
index 64818e6ca1..fdc47743fa 100644
--- a/actionpack/test/dispatch/routing_test.rb
+++ b/actionpack/test/dispatch/routing_test.rb
@@ -3706,6 +3706,24 @@ class TestRoutingMapper < ActionDispatch::IntegrationTest
     assert_equal "/bar", bar_root_path
   end
 
+  def test_nested_routes_under_format_resource
+    draw do
+      resources :formats do
+        resources :items
+      end
+    end
+
+    get "/formats/1/items.json"
+    assert_equal 200, @response.status
+    assert_equal "items#index", @response.body
+    assert_equal "/formats/1/items.json", format_items_path(1, :json)
+
+    get "/formats/1/items/2.json"
+    assert_equal 200, @response.status
+    assert_equal "items#show", @response.body
+    assert_equal "/formats/1/items/2.json", format_item_path(1, 2, :json)
+  end
+
 private
 
   def draw(&block)