* The element's ID needs to be registered so that it can be found.
*/
public void test_signature_with_ID() throws Exception {
String file = "envelopingSignature.xml";
DOMValidateContext vc = validator.getValidateContext
(file, new KeySelectors.KeyValueKeySelector());
Document doc = vc.getNode().getOwnerDocument();
NodeList nl = doc.getElementsByTagName("Assertion");
vc.setIdAttributeNS((Element) nl.item(0), null, "AssertionID");
boolean coreValidity = validator.validate(vc);
assertTrue("Signature failed core validation", coreValidity);
}