Requiring nokogiri/version does not fully define Nokogiri::VERSION

[headius]

When requiring just 'nokogiri/version', the Nokogiri::VERSION errors, likely because the JRuby extension does not load.

$ jruby -e 'require "nokogiri/version"; Nokogiri::VERSION'
NameError: uninitialized constant Nokogiri::XERCES_VERSION
      const_missing at org/jruby/RubyModule.java:3742
            to_hash at /Users/headius/projects/jruby/lib/ruby/gems/shared/gems/nokogiri-1.10.2-java/lib/nokogiri/version.rb:74
  <module:Nokogiri> at /Users/headius/projects/jruby/lib/ruby/gems/shared/gems/nokogiri-1.10.2-java/lib/nokogiri/version.rb:100
             <main> at /Users/headius/projects/jruby/lib/ruby/gems/shared/gems/nokogiri-1.10.2-java/lib/nokogiri/version.rb:1
            require at org/jruby/RubyKernel.java:987
             (root) at /Users/headius/projects/jruby/lib/ruby/stdlib/rubygems/core_ext/kernel_require.rb:1
             <main> at /Users/headius/projects/jruby/lib/ruby/stdlib/rubygems/core_ext/kernel_require.rb:130

The constant should get defined within version.rb or it should require in what it needs for this constant.

[flavorjones]

Hi @headius,

I think you're assuming a contract where one doesn't exist. The file nokogiri/version.rb has never been intended to be required by itself, because (as you point out in #1899) the underlying libraries aren't guaranteed to have been loaded.

Can you help me understand why you want to load this file individually? Specifics about your use case would really help. I imagine it's because many gems have an implicit contract that you can more-cheaply get version info if only that file is loaded, and you'd like that here -- but I'd like to validate that assumption.

The change you've made in #1899 does introduce that contract; but only for JRuby. It may be worth pointing out that currently this contract does not exist for CRuby, either:

ruby -ryaml -rnokogiri/version -e 'puts Nokogiri::VERSION_INFO.to_yaml'
---
warnings: []
nokogiri: 1.10.3
ruby:
  version: 2.6.2
  platform: x86_64-linux
  description: ruby 2.6.2p47 (2019-03-13 revision 67232) [x86_64-linux]
  engine: ruby

modulo that in CRuby, no errors are raised, the constants populated by version.rb do not include the underlying libraries.

[flavorjones]

All of which is to say, I think I'm OK with introducing this contract, but I'd like it to be consistently enforced across both backends.

[flavorjones]

Oh! Ignore my above comment, I see your change in #1899 does indeed introduce that contract for CRuby as well. I'll fix the PR (which went red because the new file isn't in the Manifest (thanks, Hoe)) and merge it once it's green.

Thanks, @headius!

[flavorjones]

This will be fixed in v1.11.0. Please watch the milestone for status.