@Test(expected = XMLProcessingException.class)
public void testGetRequiredNodeAsString() {

    OMElement root = adapter.getRootElement();
    String value = adapter.getRequiredNodeAsString( root,
                                                    new XPath(
                                                               "wfs:Query/ogc:Filter/ogc:BBOX/ogc:PropertyName/text()",
                                                               nsContext ) );
    assertEquals( "app:placeOfBirth/app:Place/app:country/app:Country/app:geom", value );
    adapter.getRequiredNodeAsString( root, new XPath( "wfs:Query/@doesNotExist", nsContext ) );
}