Merge pull request rails#54655 from viralpraxis/raise-actionpack-double-render-error-on-head-after-render

Raise `DoubleRenderError` on `head` after rendering

Author: byroot

actionpack/CHANGELOG.md

@@ -1,3 +1,18 @@
+*   Raise `AbstractController::DoubleRenderError` if `head` is called after rendering.
+
+    After this change, invoking `head` will lead to an error if response body is already set:
+
+    ```ruby
+    class PostController < ApplicationController
+      def index
+        render locals: {}
+        head :ok
+      end
+    end
+    ```
+
+    *Iaroslav Kurbatov*
+
 *   The Cookie Serializer can now serialize an Active Support SafeBuffer when using message pack.
 
     Such code would previously produce an error if an application was using messagepack as its cookie serializer.

actionpack/lib/action_controller/metal/head.rb

@@ -25,6 +25,8 @@ def head(status, options = nil)
         raise ArgumentError, "#{status.inspect} is not a valid value for `status`."
       end
 
+      raise ::AbstractController::DoubleRenderError if response_body
+
       status ||= :ok
 
       if options

actionpack/test/controller/new_base/render_test.rb

@@ -49,6 +49,13 @@ def index
     end
   end
 
+  class DoubleRenderWithHeadController < ActionController::Base
+    def index
+      render plain: "hello"
+      head :bad_request
+    end
+  end
+
   class ChildRenderController < BlankRenderController
     append_view_path ActionView::FixtureResolver.new("render/child_render/overridden_with_own_view_paths_appended.html.erb" => "child content")
     prepend_view_path ActionView::FixtureResolver.new("render/child_render/overridden_with_own_view_paths_prepended.html.erb" => "child content")
@@ -83,6 +90,20 @@ class RenderTest < Rack::TestCase
         end
       end
     end
+
+    test "using head after rendering raises an exception" do
+      with_routing do |set|
+        set.draw do
+          ActionDispatch.deprecator.silence do
+            get ":controller", action: "index"
+          end
+        end
+
+        assert_raises(AbstractController::DoubleRenderError) do
+          get "/render/double_render_with_head", headers: { "action_dispatch.show_exceptions" => :none }
+        end
+      end
+    end
   end
 
   class TestOnlyRenderPublicActions < Rack::TestCase