Use external facter for unit testing facts: spec/helpers/external_facter_helper.rb

external_facter_helper.rb

require 'yaml'

module RSpecHelper
  module SystemFacter

    def self.resolve_fact (fact, stubs = {}, facter_path = (ENV['FACTER_PATH'] || '/usr/bin/facter'))
      env_values = {}
      command = [ facter_path, '--yaml']

      facts_path = File.expand_path(File.dirname(__FILE__) + '/../../lib/facter')

      stubs.each do |key,value|
        env_values["FACTER_#{key}"] = value
      end
      env_values['FACTERLIB'] = facts_path
      command += [ fact ]

      result_yaml = ''
      IO.popen(env_values, command.flatten) do |io|
        result_yaml = io.read
      end
      result_hash = YAML.load(result_yaml)
      result_hash[fact]
    end
  end
end


if RSpecHelper::SystemFacter.resolve_fact('facterversion') !~ /^3/
  raise "Wrong facter system version detected: 'RSpecHelper::SystemFacter.resolve_fact('facterversion')"
end