### Question:
XPathHelper { public static String addXhtmlNsToXPath(Document document, String xPath) { Validate.notNull(document, "document must not be null."); Validate.notEmpty(xPath, "xPath must not be empty."); String returnValue = xPath; if (hasXhtmlNs(document)) { returnValue = addXhtmlNsToXPath(xPath); } return returnValue; } private  XPathHelper(); static List<Node> getNodes(Node node, String xPath, Map<String, String> namespaces); static List<Node> getNodes(Node node, String xPath); static Node getNode(Node node, String xPath, Map<String, String> namespaces); static Node getNode(Node node, String xPath); static Node getNodeByID(Node node, String nodeId); static Node getParentNodeByID(Node node, String nodeId); static String getNodeTextContent(Node node, String xPath); static String getXhtmlNodeTextContent(Node node, String xPath); static String getParentXPath(String xPath); static List<Node> getPreviousSiblings(Node node); static List<Node> getXhtmlNodes(Document document, String xPath); static List<Node> getXhtmlNodes(Node node, String xPath); static Node getXhtmlNode(Document document, String xPath); static Node getXhtmlNode(Node node, String xPath); static boolean hasXhtmlNs(Document document); static String addXhtmlNsToXPath(Document document, String xPath); static String addXhtmlNsToXPath(String xPath);  }### Answer:
@Test public void testAddNamespaceToXPath() { assertEquals(" assertEquals(" assertEquals(" assertEquals(" assertEquals(" assertEquals(" assertEquals("/xhtml:TABLE/xhtml:TR/xhtml:TD/xhtml:A[4]", XPathHelper.addXhtmlNsToXPath("/TABLE/TR/TD/A[4]")); assertEquals("/xhtml:TABLE/xhtml:TR[2]/xhtml:TD/xhtml:A", XPathHelper.addXhtmlNsToXPath("/TABLE/TR[2]/TD/A")); assertEquals("/xhtml:TABLE/xhtml:TR[2]/xhtml:TD/xhtml:A/text()", XPathHelper.addXhtmlNsToXPath("/TABLE/TR[2]/TD/A/text()")); assertEquals(" assertEquals("xhtml:img", XPathHelper.addXhtmlNsToXPath("img")); assertEquals(" assertEquals(" assertEquals( " XPathHelper.addXhtmlNsToXPath(" assertEquals(" assertEquals(" assertEquals(" assertEquals(" assertEquals(" }