Ignore empty tags in xmlunit

Question

Is there any way to completely ignore an empty tag in XMLUnit so that it is not taken into account for comparison? Ex:

<a>
<b/>
<c>data1</c>
<d>data2</d>
</a>

and

<a>
<c>data1</c>
<d>data2</d>
</a>

should not return any difference. Is there any inbuilt function for doing this? Thank you.

Answer 1

In general an empty tag is not the same as a missing tag, that's why XMLUnit complains. In XMLUnit 2.x you can suppress the comparison of nodes with a NodeFilter. NodeFilter is a predicate function that accepts a single DOM Node and returns true if the node should be considered while comparing documents. The default-implementation simply returns true for all Nodes that are not the document type declaration.

You could use something like the following (untested) class

class SuppressEmptyElements implements Predicate<Node> {
    @Override
    public boolean test(Node n) {
        if (n instanceof Element) {
            return !isEmpty((Element) n);
        }
        // not an element - a commment, nested text and so on
        return true;
    }

    private boolean isEmpty(Element e) {
        return e.getAttributes().getLength() == 0 && e.getChildNodes().getLength() == 0;
    }
}

When using DiffBuilder you'd use something like withNodeFilter(new SuppressEmptyElements()). The longer story can be found in XMLUnit's user guide.