fails:String#encode given the :xml => :text option replaces undefined characters with their upper-case hexadecimal numeric character references
fails:String#encode given the :xml => :attr option replaces undefined characters with their upper-case hexadecimal numeric character references
fails:String#encode! given the :xml => :text option replaces undefined characters with their upper-case hexadecimal numeric character references
fails:String#encode! given the :xml => :attr option replaces undefined characters with their upper-case hexadecimal numeric character references
