[SOLVED] How do I ignore certain elements when comparing XML?

How do I ignore certain elements when comparing XML?

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.

Solution

Things have changed a lot for XMLUnit since this question was answered.

You can now easily ignore a node when using a DiffBuilder:

final Diff documentDiff = DiffBuilder
            .compare(expectedSource)
            .withTest(actualSource)
            .withNodeFilter(node -> !node.getNodeName().equals(someName))
            .build();

If you then call documentDiff.hasDifferences() nodes added to filter will be ignored.