configure zeitwerk to be okay with our generators in local generated …

…app ./lib/generators

Not sure why we are generating a generator INTO the local test app. But rather than figure this out and change it, we want to make zeitwerk okay with it.

We are telling zeitwerk to ignore the WHOLE RAILS_ROOT/lib/generators directory, just to deal with the one test_app_generator.rb file we are putting there. But hopefully that is okay.

lib/blacklight/engine.rb

@@ -6,6 +6,15 @@ module Blacklight
   class Engine < Rails::Engine
     engine_name "blacklight"
 
+    config.before_configuration do
+      # see https://github.com/fxn/zeitwerk#for_gem
+      # Blacklight puts a generator into LOCAL APP lib/generators, so tell
+      # zeitwerk to ignore the whole directory? If we're using zeitwerk
+      if Rails.autoloaders&.main.respond_to?(:ignore)
+        Rails.autoloaders.main.ignore(Rails.root.join('lib/generators'))
+      end
+    end
+
     config.after_initialize do
       Blacklight::Configuration.initialize_default_configuration
     end