gistfile1.rb

if Rails.env.development?
  lambda do
    forbidden_files = ['active_support/core_ext/object/to_json']
    
    module Kernel
      def require_with_dont_load_forbidden_files(name)
        if forbidden_files.include?(name)
          raise LoadError, "#{name} is forbidden"
        end
        require_without_dont_load_forbidden_files(name)
      end
      alias_method_chain :require, :dont_load_forbidden_files
    end
    
    forbidden_files.each do |f|
      raise LoadError, "someone loaded a forbidden file: #{f}" if $".include?(f)
    end
  end.call
end