(#4989) Add xendomains fact

Parses `/usr/sbin/xm list` and returns a comma-separated list of
domains. Based on a patch submitted by Jonas Genannt.

lib/facter/util/xendomains.rb

@@ -0,0 +1,10 @@
+# A module to gather running Xen Domains
+#
+module Facter::Util::Xendomains
+  def self.get_domains
+    if xm_list = Facter::Util::Resolution.exec('/usr/sbin/xm list')
+      domains = xm_list.split("\n").reject { |line| line =~ /^(Name|Domain-0)/ }
+      domains.map { |line| line.split(/\s/)[0] }.join(',')
+    end
+  end
+end

lib/facter/xendomains.rb

@@ -0,0 +1,10 @@
+require 'facter/util/xendomains'
+
+Facter.add("xendomains") do
+  confine :kernel => %w{Linux FreeBSD OpenBSD SunOS}
+  confine :virtual => 'xen0'
+
+  setcode do
+    Facter::Util::Xendomains.get_domains
+  end
+end

spec/unit/data/xendomains

@@ -0,0 +1,4 @@
+Name                                        ID   Mem VCPUs      State   Time(s)
+Domain-0                                     0   656     4     r-----  48140.9
+web01                                       48   512     2     -b----  97651.5
+mailserver                                  53   512     4     -b----   7536.1

spec/unit/util/xendomains.rb

@@ -0,0 +1,23 @@
+#!/usr/bin/env ruby
+
+require File.dirname(__FILE__) + '/../../spec_helper'
+
+require 'facter/util/xendomains'
+
+describe Facter::Util::Xendomains do
+  describe ".get_domains" do
+    it "should return a list of running Xen Domains on Xen0" do
+      sample_output_file = File.dirname(__FILE__) + '/../data/xendomains'
+      xen0_domains = File.read(sample_output_file)
+      Facter::Util::Resolution.stubs(:exec).with('/usr/sbin/xm list').returns(xen0_domains)
+      Facter::Util::Xendomains.get_domains.should == %{web01,mailserver}
+    end
+
+    context "when xm list isn't executable" do
+      it "should be nil" do
+        Facter::Util::Resolution.stubs(:exec).with('/usr/sbin/xm list').returns(nil)
+        Facter::Util::Xendomains.get_domains.should == nil
+      end
+    end
+  end
+end