/**
  * Test method for {@link
  * net.hyperadapt.pxweave.interpreter.test.OperationInterpreter#interpreteChooseVariant(org.w3c.dom.NodeList)}
  * .
  *
  * @throws XMLWeaverException
  */
 @Test
 public void testInterpreteChooseVariant() throws XMLWeaverException {
   final NodeList joinPoints = xPathEvaluator.evaluateXPath("//books:book[1]", document);
   oInterpreter.interpreteChooseVariant(joinPoints);
   assertTrue(
       "only one variant should be left",
       xPathEvaluator.evaluateXPath("//books:book", document).getLength() == 1);
   assertTrue(
       "the variant left should be the right one",
       (xPathEvaluator
           .evaluateXPath("//books:book/books:author/books:name", document)
           .item(0)
           .getTextContent()
           .contentEquals("Sam")));
 }