How to produce integer literal as an attribute in Scala XML output?

I expect the following code to produce XML value with the following content:

<TestInteger value="10"/>

Compiler gives of an error

scala> import scala.xml._
import scala.xml._
scala> val x:Int = 10
x: Int = 10
scala> <TestInteger value={x}/>
<console>:8: error: overloaded method constructor UnprefixedAttribute with alternatives (String,Option[Seq[scala.xml.Node]],scala.xml.MetaData)scala.xml.UnprefixedAttribute <and> (String,String,scala.xml.MetaData)scala.xml.UnprefixedAttribute <and> (String,Seq[scala.xml.Node],scala.xml.MetaData)scala.xml.UnprefixedAttribute cannot be applied to (java.lang.String,Int,scala.xml.MetaData)
       <TestInteger value={x}/>

What am I doing wrong? Are integer literals allowed in XML?

I'm using Scala 2.7.7

Solution

Look like your XML is violating XML specification according to this each attribute value must begin with a double quote. See AttValue rule.
Edit:
After some googling around it seems that scala.xml.UnprefixedAttribute has Constructor that only supports strings as values so since there is no build-in implicit conversion from Int's to String this code of yours will not work same as code :

val a : String = 10

Scala doesn't now how convert integers to strings automatically but following code however will work

implicit def intToString(i:Int) = i.toString  
val a : Int = 10
val b  = <Test attr={a}/>