[Xmlunit-general] Revisiting Node Selection

[Stefan B. <bo...@ap...>]

Hi,

most if not all bug reports and user questions somehow boil down to
finding the best strategy to make XMLUnit pick matching elements - and
the 1.3 code isn't always obvious.

I've changed trunk so that the whole strategy of selecting the best
matching nodes among the children of test and control elements is
pluggable:

    /**
     * Matches control and test nodes against each other, returns the
     * matching pairs.
     */
    Iterable<Map.Entry<Node, Node>> match(Iterable<Node> controlNodes,
                                          Iterable<Node> testNodes);

and

    IEnumerable<KeyValuePair<XmlNode, XmlNode>>
        Match(IEnumerable<XmlNode> controlNodes,
              IEnumerable<XmlNode> testNodes);


I'm thinking of making the parent Node or its XPath (or both) available
as well.

The default strategy picks non-element nodes in order if they are of the
same type (where CDATA and Text are the same type) and uses an
ElementSelector (2.x term for ElementQualifier) for elements.

The legacy layer can replace this with a strategy that adds the
compareUnmatched logic.

I'm also thinking of making ElementSelector allow some sort of middle
ground where it can say "yes the nodes match" and "I know the nodes
don't match" as well as "they don't really look like my business".  For
example if an ElementNameAndAttributeQualifier is asked to compare
elements that don't have any attributes.  This may allow us to pick a
fallback strategy.

It may even be possible to provide a builder with a conditional
strategy, something like "for foo elements, check the bar attribute -
for baz elements compare the nested text of xyzzy elements" which might
look like

    NodeMatcher nm = NodeMatcherBuilder.setDefault(ElementSelectors.byName)
        .if(ElementName.is("foo"))
        .use(ElementSelectors.byNameAndAttributes("bar"))
        .if(ElementName.is("baz"))
        .use(ElementSelectors.byNameAndNestedTextRec(".//xyzzy"))
        .build();

Does that sound reasonable?

Stefan