Mailer preview now uses `url_for` to fix links to emails for apps running on a subdirectory, closes #19092.

1 files changed, 30 insertions, 0 deletions

diff --git a/railties/test/application/mailer_previews_test.rb b/railties/test/application/mailer_previews_test.rb
index 83501a7f11..1835d42c82 100644
--- a/railties/test/application/mailer_previews_test.rb
+++ b/railties/test/application/mailer_previews_test.rb
@@ -454,6 +454,36 @@ module ApplicationTests
       assert_match '<option selected value="?part=text%2Fplain">View as plain-text email</option>', last_response.body
     end
 
+    test "mailer previews create correct links when loaded on a subdirectory" do
+      mailer 'notifier', <<-RUBY
+        class Notifier < ActionMailer::Base
+          default from: "from@example.com"
+
+          def foo
+            mail to: "to@example.org"
+          end
+        end
+      RUBY
+
+      text_template 'notifier/foo', <<-RUBY
+        Hello, World!
+      RUBY
+
+      mailer_preview 'notifier', <<-RUBY
+        class NotifierPreview < ActionMailer::Preview
+          def foo
+            Notifier.foo
+          end
+        end
+      RUBY
+
+      app('development')
+
+      get "/rails/mailers", {}, 'SCRIPT_NAME' => '/my_app'
+      assert_match '<h3><a href="/my_app/rails/mailers/notifier">Notifier</a></h3>', last_response.body
+      assert_match '<li><a href="/my_app/rails/mailers/notifier/foo">foo</a></li>', last_response.body
+    end
+
     private
       def build_app
         super