JUnit Test if XML Document is sorted on arbitrary column

Question

Given an xml document like

<root>
  <row>
    <a>2</a>
    <b>1</b>
    <c>8</c>
  </row>
  <row>
    <b>5</b>
    <a>2</a>
    <c>8</c>
  </row>
  <row>
    <a>2</a>
    <c>8</c>
    <b>6</b>
  </row>
</root>

Is there an easy way to assert that the XML document is sorted on element B in XMLUnit

Edit: I have an odd problem with a piece of software that I can not change where the value of the XML tags in any given node needs to be in a specific order. I'd like it for my test harness to enforce this set of rules before any other validation.

I can't think of any (but then again, I don't know XmlUnit et al). Why do you want to do this? Is this the output of some method to be tested? Can you refactor the code to produce output in a more testable format? — Péter Török, Apr 26 '10 at 20:23
@Peter, I'm dealing with some legacy software where the XML needs to be in a quirky format. I'd like to make sure my xml output always obeys those quirky rules. — sal, Apr 26 '10 at 21:29
Good Question (+1). See my answer for a very simple solution. :) — Dimitre Novatchev, Apr 27 '10 at 12:57

score 2 · Accepted Answer · answered Apr 27 '10 at 12:56

2

Use the value of the following simple XPath 1.0 expression:

not(//b[. > following::b])

answered Apr 27 '10 at 12:56

Dimitre Novatchev

240,661
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This is almost what I wanted. I got my solution after looking at this. Thanks! – sal Apr 27 '10 at 18:25
Hey sal, what IS your solution? – belwood Sep 03 '10 at 19:14
@belwood: @sal says that he put this XPath expression in his code -- probably the real column names were different. If you have the same problem, this answer should get you going. – Dimitre Novatchev Sep 03 '10 at 19:33

score 1 · Answer 2 · answered Apr 26 '10 at 21:35

1

You can build an assertion around an XPath selection.

Probably the simplest way would be to use the XPath expression /root/row/b, request the NODESET result type, then copy the text from each result node into a List structure. You can assert that the text in that list is equal to an "expected" list created with the Arrays.asList() method (I'm assuming you're using Java).

answered Apr 26 '10 at 21:35

Anon

126
1

This was what I was doing and I wasn't happy with it. For starters, there was too much code that was specific to a particular test and more code that might have to change as my code changed. – sal Apr 27 '10 at 18:24

score 1 · Answer 3 · answered Apr 27 '10 at 06:33

1

If you can execute XQuery, then the XQuery assertion:

every $i in (1 to count ($x/row) - 1)
satisfies 
   let $j :=  $i + 1   
   return number($x/row[$i]/b) <= number($x/row[$j]/b)

where $x is the document, is true if the rows are in ascending order of b, false otherwise

answered Apr 27 '10 at 06:33

Chris Wallace

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I'm too junior to comment on Dimitre's neat answer but shouldn't it be not($x//b[number(.) > following::b/number(.)]) for this numeric data and isnt this O N^2 since every b is compared with all the following b's? – Chris Wallace Apr 27 '10 at 14:15

JUnit Test if XML Document is sorted on arbitrary column

3 Answers3