add mdadm fact

lib/facter/mdadm.rb

@@ -0,0 +1,6 @@
+Facter.add('mdadm') do
+  confine :kernel => 'Linux'
+  setcode do
+    Facter::Util::Resolution.which('mdadm')
+  end
+end

spec/unit/facts/mdadm_spec.rb

@@ -0,0 +1,14 @@
+require 'spec_helper'
+
+describe 'mdadm', :type => :fact do
+  before(:each) { Facter.clear }
+
+  context 'kernel => Linux' do
+    it 'should find the executable' do
+      Facter.fact(:kernel).stubs(:value).returns('Linux')
+      Facter::Util::Resolution.stubs(:which).with('mdadm').returns('/sbin/mdadm')
+
+      Facter.fact(:mdadm).value.should == '/sbin/mdadm'
+    end
+  end
+end