How do I ignore certain elements when comparing XML?

Question

I have an XML message like so:

<root>   <elementA>something</elementA>   <elementB>something else</elementB>   <elementC>yet another thing</elementC> </root> 

I want to compare a message of this type produced by a method under test to an expected message, but I don't care about elementA. So, I'd like the above message to be considered equal to:

<root>   <elementA>something different</elementA>   <elementB>something else</elementB>   <elementC>yet another thing</elementC> </root> 

I'm using the latest version of XMLUnit.

I'm imagining that the answer involves creating a custom DifferenceListener; I just don't want to reinvent the wheel if there's something ready to use out there.

Suggestions that use a library other than XMLUnit are welcome.

Answer 1

I wound up implementing a DifferenceListener that takes a list of node names (with namespaces) to ignore textual differences for:

public class IgnoreNamedElementsDifferenceListener implements DifferenceListener {     private Set<String> blackList = new HashSet<String>();      public IgnoreNamedElementsDifferenceListener(String ... elementNames) {         for (String name : elementNames) {             blackList.add(name);         }     }      public int differenceFound(Difference difference) {         if (difference.getId() == DifferenceConstants.TEXT_VALUE_ID) {             if (blackList.contains(difference.getControlNodeDetail().getNode().getParentNode().getNodeName())) {                 return DifferenceListener.RETURN_IGNORE_DIFFERENCE_NODES_IDENTICAL;             }         }          return DifferenceListener.RETURN_ACCEPT_DIFFERENCE;     }      public void skippedComparison(Node node, Node node1) {      } }