XML / CSS resource selector for Inspec

xml_css.rb

require 'nokogiri'
require 'utils/simpleconfig'

class XML_CSS < Inspec.resource(1)
  name 'xml_css'

  desc 'XML for Chef Inspec using Nokogiri\'s CSS selector feature'

  example '
    Given this set of XML:

        <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
        <this>
          <but>
            <some>XML</some>
          </but>
          <but>
            <some>More</some>
          </but>
        </this>

      Run this

      describe xml_css "/tmp/file.xml", "but+but" do
        its("inner_text") { should eq "More" }
      end

    The CSS is being put as a second variable in the describe block so we
    can blindly call the its-descriptor as a Nokogiri::XML::NodeSet-method.
    This way, not only to_s, to_a but also empty? and length are working as
    expected.
  '

  def initialize(filename, xpath)
    @file = inspec.file(filename)
    @file_content = @file.content

    # check if file is available
    if !@file.file?
      skip_resource "Can't find file \"#{@path}\""
      return @params = {}
    end

    # check if file is readable
    if @file_content.nil? && !@file.empty?
      skip_resource "Can't read file \"#{@path}\""
      return @params = {}
    end
    begin
      doc = Nokogiri::XML(@file_content) do |config|
        config.options = Nokogiri::XML::ParseOptions::NOERROR
      end
      doc.remove_namespaces!
    rescue
      unless doc.is_a?(Nokogiri::XML::Document)
        skip_resource "Error parsing #{@file}'s XML!"
      end
    end
    @object = doc.root.css(xpath)
    @type = @object.class
    skip_resource "#{@file}'s XML doesn't yielded nil at css-path #{xpath}" if @type.nil?
  end

  def method_missing(*keys)
    skip_resource 'Please specify a method to call!' unless keys[0].is_a? String
    skip_resource 'Unknown method called!' unless @object.methods.include? keys[0]
    return @object.send keys[0].to_sym
  end
end

Another form (for parsing once then re-querying all over the place):

require 'nokogiri'
require 'utils/simpleconfig'

class XML_CSS < Inspec.resource(1)
  name 'xml_css'

  desc 'XML for Chef Inspec using Nokogiri\'s CSS selector feature'

  example '
    Given this set of XML:

        <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
        <this>
          <but>
            <some>XML</some>
          </but>
          <but>
            <some>More</some>
          </but>
        </this>

      Run this

      describe xml_css "/tmp/file.xml" do
        its("but + but !! inner_text") { should eq "More" }
      end

    The CSS is being put as a second variable in the describe block so we
    can blindly call the its-descriptor as a Nokogiri::XML::NodeSet-method.
    This way, not only to_s, to_a but also empty? and length are working as
    expected.
  '

  def initialize(filename)
    @file = inspec.file(filename)
    @file_content = @file.content

    # check if file is available
    if !@file.file?
      skip_resource "Can't find file \"#{@path}\""
      return @params = {}
    end

    # check if file is readable
    if @file_content.nil? && !@file.empty?
      skip_resource "Can't read file \"#{@path}\""
      return @params = {}
    end
    begin
      doc = Nokogiri::XML(@file_content) do |config|
        config.options = Nokogiri::XML::ParseOptions::NOERROR
      end
      doc.remove_namespaces!
    rescue
      unless doc.is_a?(Nokogiri::XML::Document)
        skip_resource "Error parsing #{@file}'s XML!"
      end
    end
    @object = doc
    @type = @object.class
    skip_resource "#{@file}'s XML doesn't yielded nil at css-path #{xpath}" if @type.nil?
  end

  def method_missing(selector)
    keys = selector.to_s.split(' !! ')
    @object.root.css(keys[0]).send(keys[1].to_sym)
  end
end