read configuration to determine excluded eager loaded directory (#36354)

* read config/webpacker.yml to determine which path to exclude for zeitwerk:check

* fix test errors

* more changes to fix test errors

* refactor webpacker_path

[Andrew Kress + Rafael Mendonça França]

2 files changed, 11 insertions, 2 deletions

diff --git a/railties/lib/rails/engine/configuration.rb b/railties/lib/rails/engine/configuration.rb
index 4143b3c881..612bd170c6 100644
--- a/railties/lib/rails/engine/configuration.rb
+++ b/railties/lib/rails/engine/configuration.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "rails/railtie/configuration"
+require "yaml"
 
 module Rails
   class Engine
@@ -40,7 +41,7 @@ module Rails
 
           paths.add "app",                 eager_load: true,
                                            glob: "{*,*/concerns}",
-                                           exclude: %w(assets javascript)
+                                           exclude: ["assets", webpacker_path]
           paths.add "app/assets",          glob: "*"
           paths.add "app/controllers",     eager_load: true
           paths.add "app/channels",        eager_load: true, glob: "**/*_channel.rb"
@@ -85,6 +86,14 @@ module Rails
       def autoload_paths
         @autoload_paths ||= paths.autoload_paths
       end
+
+      def webpacker_path
+        if File.file?("#{Rails.root}/config/webpacker.yml")
+          YAML.load_file("#{Rails.root}/config/webpacker.yml")[Rails.env]["source_path"]&.gsub("app/", "")
+        else
+          "javascript"
+        end
+      end
     end
   end
 end
diff --git a/railties/test/application/configuration_test.rb b/railties/test/application/configuration_test.rb
index 96678c395c..38dda20bec 100644
--- a/railties/test/application/configuration_test.rb
+++ b/railties/test/application/configuration_test.rb
@@ -1708,7 +1708,7 @@ module ApplicationTests
       app "development"
       ActiveSupport::Dependencies.autoload_paths.each do |path|
         assert_not_operator path, :ends_with?, "app/assets"
-        assert_not_operator path, :ends_with?, "app/javascript"
+        assert_not_operator path, :ends_with?, "app/#{Rails.configuration.webpacker_path}"
       end
     end