Zeitwerk should ignore preview files when previews are disabled

[palkan]

Discussed in #24

^{Originally posted by dhnaranjo September 23, 2022}
Hello! So I'm trying to do the following:

• keeping Preview files in app/components/component_name
• building previewed objects using FactoryBot and Faker
• including FactoryBot::Syntax::Methods in ApplicationViewComponentPreview so I can call build instead of FactoryBot.build
• excluding FactoryBot from my Production environment

The result is that when my app directory is eager loaded in Production it gets all upset that FactoryBot::Syntax::Methods doesn't exist. To fix this I put together an initializer looks a lil something like this:

# config/initializers/zeitwerk_view_component_previews.rb

unless Rails.env.development? || Rails.env.test?
  Rails.autoloaders.each do |autoloader|
    autoloader.ignore(
      Rails.application.config.view_component.preview_paths.flat_map { Pathname(_1).glob("**/*preview.rb") }
    )
  end
end

I think this is a pretty good idea to include something like this here so other folks can avoid this particular dumb trap.