After marshalling/unmarshalling nil is frozen

[warnergodfrey]

Marshalling or unmarshalling an XML document using ROXML is freezing nil.

I have included a failing spec that demonstrates the issue and a copy of the Gemfile and rvm config that was used to run the spec.

frozen_nil_spec.rb

require 'rubygems'
require 'roxml'

describe 'roxml' do
  let(:xml_file) { File.open(File.expand_path('library.xml', File.dirname(__FILE__))) }

  context 'before unmarshalling an XML document' do
    it { nil.should_not be_frozen }
  end

  context 'after unmarshalling an XML document' do
    before do
      lib = Library.from_xml(xml_file)
    end

    it { nil.should_not be_frozen }
  end
end

class Book
  include ROXML

  xml_accessor :isbn, :from => "@ISBN" # attribute with name 'ISBN'
  xml_accessor :title
  xml_accessor :description, :cdata => true  # text node with cdata protection
  xml_accessor :author
end


class Library
  include ROXML

  xml_accessor :name, :from => "NAME", :cdata => true
  xml_accessor :books, :as => [Book] # by default roxml searches for books for in <book> child nodes, then, if none are present, in ./books/book children
end

rspec output

.F

Failures:

  1) roxml after unmarshalling an XML document 
     Failure/Error: it { nil.should_not be_frozen }
       expected frozen? to return false, got true
     # ./spec/frozen_nil_spec.rb:16:in `block (3 levels) in <top (required)>'

Finished in 0.00151 seconds
2 examples, 1 failure

Failed examples:

rspec ./spec/frozen_nil_spec.rb:16 # roxml after unmarshalling an XML document 

library.xml

<?xml version="1.0"?>
<library>
  <NAME><![CDATA[Favorite Books]]></NAME>
  <book ISBN="0201710897">
    <title>The PickAxe</title>
    <description><![CDATA[Best Ruby book out there!]]></description>
    <author>David Thomas, Andrew Hunt, Dave Thomas</author>
  </book>
</library>

Gemfile

source 'http://rubygems.org'

gem 'roxml', '3.2.0'
gem 'rspec', '2.6.0'
gem 'i18n'

Gemfile.lock

GEM
  remote: http://rubygems.org/
  specs:
    activesupport (3.1.3)
      multi_json (~> 1.0)
    diff-lcs (1.1.3)
    i18n (0.6.0)
    multi_json (1.0.4)
    nokogiri (1.5.0)
    roxml (3.2.0)
      activesupport (>= 2.3.0)
      nokogiri (>= 1.3.3)
    rspec (2.6.0)
      rspec-core (~> 2.6.0)
      rspec-expectations (~> 2.6.0)
      rspec-mocks (~> 2.6.0)
    rspec-core (2.6.4)
    rspec-expectations (2.6.0)
      diff-lcs (~> 1.1.2)
    rspec-mocks (2.6.0)

PLATFORMS
  ruby

DEPENDENCIES
  i18n
  roxml (= 3.2.0)
  rspec (= 2.6.0)

.rvmrc

rvm 1.9.2-p290@roxml --create

[Empact]

Thanks Warner for the great bug report. I believe I have this fixed, and have it released as 3.2.1. The problem in this case was related to overzealous freezing of the roxml_naming_convention attribute, which is sometimes nil. In hindsight I don't really see the point in freezing it so I've dropped that altogether.

Now I have some questions about the freezing behavior in roxml (i.e. when one supplies the :frozen option to an attribute) and whether they can lead to similar behavior, so I've tried to diminish those possibilities, but they still are present I believe.

Thanks again for the report!