Comparing two XML strings/files in Groovy/Java

Question

I'm writing unit tests for checking some XML builder.

Now I'm running into the problem of syntactical differences between the expected result and the actual result, despite their identical semantics.

Example:

Expected result:

<parent><child attr="test attribute">text here</child></parent>

Actual result:

<parent>
  <child attr="test attribute">
    text here
  </child>
</parent>

I tried normalizing the xml using XmlUtil.serialize(), however this seems to keep the whitespaces, leaving syntactical differences.

How can I get the normalized/canonical form of xml strings in order to make my tests more robust?

I'm writing a Grails application, so I'm fine with any solution in Groovy or Java.

Answer 1

The question and the accepted answer (as of today) correspond to a legacy version of XMLUnit.

For those interested in knowing how to do it with XMLUnit v2 on Groovy:

def "XMLs must be identical"() {
    setup:
    def control = '<foo><bar></bar></foo>'
    def test = '''
        <foo>
          <bar></bar>
        </foo>
    '''

    when:
    Diff d = DiffBuilder.compare(Input.fromString(control))
        .withTest(Input.fromString(test))
        .ignoreWhitespace()
        .ignoreComments()
        .normalizeWhitespace()
        .build()

    then:
    !d.hasDifferences()
}

Perhaps there is a "groovier" way of doing it but I think it's OK for illustration purposes :)