add tests for users with sid on windows

test/integration/default/user_spec.rb

@@ -76,6 +76,8 @@ end
 if os.windows?
   describe user(userinfo[:name]) do
     it { should exist }
+    # should return the SID of the user
+    its('uid') { should_not eq nil}
   end
 else
   describe user(userinfo[:name]) do

test/unit/resources/user_test.rb

@@ -100,6 +100,7 @@ describe 'Inspec::Resources::User' do
 
   it 'read user on Windows' do
     resource = MockLoader.new(:windows).load_resource('user', 'example/Administrator')
+    _(resource.uid).wont_be_nil
     _(resource.exists?).must_equal true
     _(resource.group).must_equal nil
     _(resource.groups).must_equal ['WIN-K0AKLED332V\\Administrators', 'EXAMPLE\\Domain Admins']