zeitwerk_bug.rb

#!/usr/bin/env rvm-shebang-ruby

require 'bundler/inline'
gemfile do
  source 'https://rubygems.org'
  gem 'zeitwerk'
  gem 'byebug'
end

require 'pp'
require 'tmpdir'
require 'logger'
require 'pathname'

class ZeitwerkTester
  attr_reader :order, :silent, :logger
  def initialize(order:, silent: true)
    @order = order
    @silent = silent
    @logger = Logger.new(@silent ? '/dev/null' : STDERR)
  end

  def parent_dir
    @parent_dir ||= Pathname.new(Dir.mktmpdir)
  end

  def subdir
    @subdir ||= (parent_dir / 'subdir').tap(&:mkpath)
  end

  def parent_dir_loader
    @parent_dir_loader ||= Zeitwerk::Loader.new.tap do |loader|
      loader.logger = logger
      loader.log!

      loader.ignore(subdir)
      loader.push_dir(parent_dir)
      loader.collapse(parent_dir)

      loader.enable_reloading
      loader.setup
      loader.eager_load
    end
  end

  def subdir_loader
    @subdir_loader ||= Zeitwerk::Loader.new.tap do |loader|
      loader.logger = logger
      loader.log!

      loader.push_dir(subdir)
      loader.collapse(subdir)

      loader.enable_reloading
      loader.setup
      loader.eager_load
    end
  end

  def load!
    puts "Now testing loading `parent_dir` and `subdir` in #{order} order:"

    case order
    when :normal
      parent_dir_loader
      subdir_loader
    when :reverse
      subdir_loader
      parent_dir_loader
    else
      raise ArgumentError, 'Invalid argument'
    end
  rescue Zeitwerk::Error => ex
    puts "An exception was raised by Zeitwerk while loading in #{order} order:"
    pp ex unless silent
    :failed
  else
    puts "Loading was successful in #{order} order."
    :succeeded
  end

  def cleanup!
    return unless parent_dir&.exist?

    parent_dir.rmtree
    true
  end

  def run!
    load!
  ensure
    cleanup!
    puts
  end

  class << self
    def test!(silent:)
      puts "Will test loading two dirs: `parent_dir` and `subdir` in both orders:"
      puts
      %i[normal reverse].map do |order|
        [ order, new(order: order, silent: silent).run! ]
      end.to_h
    end
  end
end

pp ZeitwerkTester.test!(silent: ARGV.first.nil?)