optimizes eager loading in :zeitwerk mode

During initialization, the eager load paths of engines are unshifted
into AS::Dependencies.autoload_paths. After that, the collection is
frozen. (See the initializers in railties/lib/rails/engine.rb.)

Hence, there is no eager load path that is not an autoload path too, and
so the array difference in the deleted code is always an empty array.

Just do nothing.

1 files changed, 14 insertions, 0 deletions

diff --git a/railties/test/application/zeitwerk_integration_test.rb b/railties/test/application/zeitwerk_integration_test.rb
index e4a17e5a31..a4320bbdc3 100644
--- a/railties/test/application/zeitwerk_integration_test.rb
+++ b/railties/test/application/zeitwerk_integration_test.rb
@@ -124,12 +124,26 @@ class ZeitwerkIntegrationTest < ActiveSupport::TestCase
 
     app_file "app/models/user.rb", "class User; end; $zeitwerk_integration_test_user = true"
     app_file "app/models/post.rb", "class Post; end; $zeitwerk_integration_test_post = true"
+
     boot("production")
 
     assert $zeitwerk_integration_test_user
     assert $zeitwerk_integration_test_post
   end
 
+  test "eager loading loads code in engines" do
+    $test_blog_engine_eager_loaded = false
+
+    engine("blog") do |bukkit|
+      bukkit.write("lib/blog.rb", "class BlogEngine < Rails::Engine; end")
+      bukkit.write("app/models/post.rb", "Post = $test_blog_engine_eager_loaded = true")
+    end
+
+    boot("production")
+
+    assert $test_blog_engine_eager_loaded
+  end
+
   test "eager loading loads anything managed by Zeitwerk" do
     $zeitwerk_integration_test_user = false
     app_file "app/models/user.rb", "class User; end; $zeitwerk_integration_test_user = true"