Yum.repo should show correct name

https://github.com/chef/inspec/issues/1390

Signed-off-by: Wei, He <weihe924stephen@gmail.com>

lib/resources/yum.rb

@@ -134,6 +134,10 @@ module Inspec::Resources
       return false if repo.nil?
       info['status'] == 'enabled'
     end
+
+    def to_s
+      "YumRepo #{shortname(info['id'])}"
+    end
   end
 
   # for compatability with serverspec

test/unit/resources/yum_test.rb

@@ -58,6 +58,7 @@ describe 'Inspec::Resources::YumRepo' do
     extras = resource.repo('base-debuginfo/x86_64')
     _(extras.exist?).must_equal true
     _(extras.enabled?).must_equal false
+    _(extras.to_s).must_equal 'YumRepo base-debuginfo'
   end
 
   it 'test enabled extra repo (serverspec backwards comptability)' do