Merge pull request #20889 from morgoth/fix-mailer-previews-on-not-local-requests

Fix displaying mailer previews on non local requests.

railties/CHANGELOG.md

+*   Fix displaying mailer previews on non local requests when config
+    `action_mailer.show_previews` is set
+
+    *Wojciech Wnętrzak*
+
 *   `rails server` will now honour the `PORT` environment variable
 
     *David Cornu*

railties/lib/rails/mailers_controller.rb

@@ -3,7 +3,7 @@
 class Rails::MailersController < Rails::ApplicationController # :nodoc:
   prepend_view_path ActionDispatch::DebugExceptions::RESCUES_TEMPLATE_PATH
 
-  before_action :require_local!
+  before_action :require_local!, unless: :show_previews?
   before_action :find_preview, only: :preview
 
   def index
@@ -41,6 +41,10 @@ def preview
   end
 
   protected
+    def show_previews?
+      ActionMailer::Base.show_previews
+    end
+
     def find_preview
       candidates = []
       params[:path].to_s.scan(%r{/|$}){ candidates << $` }

railties/test/application/mailer_previews_test.rb

@@ -31,7 +31,7 @@ def teardown
     test "/rails/mailers is accessible with correct configuraiton" do
       add_to_config "config.action_mailer.show_previews = true"
       app("production")
-      get "/rails/mailers"
+      get "/rails/mailers", {}, {"REMOTE_ADDR" => "4.2.42.42"}
       assert_equal 200, last_response.status
     end