How to use XMLUnit DiffBuilder to detect differences in attributes and lists of elements

Question

I need to compare two XML strings, where there is potentially changes to arbitrary attributes within a tag, as well as tags arbitrarily inserted into, or deleted from, a sequence of tags.

I have found that if I use ElementSelectors.byNameAndText I get appropriate diffs for attribute changes, unless there are sequence insertions or deletions.

I have found that if I use ElementSelectors.byNameAndAllAttributes I get appropriate diffs for tags inserted into, or deleted from, a sequence of tags, but not appropriate attributes change details.

How do I combine these two diff generating mechanisms?

Control XML

String myControlXML =
    "<?xml version='1.0' encoding='UTF-8'?>" +
    "<ns2:policy xmlns:ns2='com.xyz' version='2' id='ABCD'>" +
    "<ns2:widgets>" +
    "<ns2:widget name='foo' id='17'>" +
    "<ns2:desc text='Does foo widget stuff' version='2'/>" +
    "</ns2:widget>" +
    "<ns2:widget name='bar' id='19'>" +
    "<ns2:desc text='Does bar widget stuff' version='4'/>" +
    "</ns2:widget>" +
    "</ns2:widgets>" +
    "</ns2:policy>";

Test XML

String myTestXML1 =
    "<?xml version='1.0' encoding='UTF-8'?>" +
    "<ns2:policy xmlns:ns2='com.xyz' version='13' id='ABCD'>" +
    "<ns2:widgets>" +
    "<ns2:widget name='foo' id='17'>" +
    "<ns2:desc text='Does foo widget stuff' version='2'/>" +
    "</ns2:widget>" +
    "<ns2:widget name='bzz' id='15'>" +
    "<ns2:desc text='Does bzz widget stuff' version='6'/>" +
    "</ns2:widget>" +
    "<ns2:widget name='bar' id='19'>" +
    "<ns2:desc text='Does bar widget stuff' version='4'/>" +
    "</ns2:widget>" +
    "</ns2:widgets>" +
    "</ns2:policy>";

Diff code

Diff myDiff7 = DiffBuilder.compare(myControlXML)
    .withTest(myTestXML1)
    .withNodeMatcher(new
        DefaultNodeMatcher(ElementSelectors.byNameAndAllAttributes))
    .build();

DIFF RESULTS 1

2 diffs
  - type = child
  - message = ns2:policy:Expected child '{com.xyz}policy' but was 'null' - comparing <ns2:policy...> at /policy[1] to <NULL>

  - type = child
  - message = ns2:policy:Expected child 'null' but was '{com.xyz}policy' - comparing <NULL> to <ns2:policy...> at /policy[1]

This seems to be saying 'some attribute is different'

With the ns2:policy lines matching,

DIFF RESULTS 2

2 diffs
  - type = child nodelist sequence
  - message = widget:Expected child nodelist sequence '1' but was '2' - comparing <ns2:widget...> at /policy[1]/widgets[1]/widget[2] to <ns2:widget...> at /policy[1]/widgets[1]/widget[3]
  - type = child
  - message = widget:Expected child 'null' but was '{com.xyz}widget' - comparing <NULL> to <ns2:widget...> at /policy[1]/widgets[1]/widget[2]

This seems to be correctly saying widget[2] was moved to widget[3] and a new widget[2] was added.

With the initial XML values, but using ElementSelectors.byNameAndText instead of ElementSelectors.byNameAndAllAttributes

DIFF RESULTS 3

6 diffs
  - type = attribute value
  - message = Expected attribute value '2' but was '13' - comparing <ns2:policy version="2"...> at /policy[1]/@version to <ns2:policy version="13"...> at /policy[1]/@version
  - type = attribute value
  - message = Expected attribute value '19' but was '15' - comparing <ns2:widget id="19"...> at /policy[1]/widgets[1]/widget[2]/@id to <ns2:widget id="15"...> at /policy[1]/widgets[1]/widget[2]/@id
  - type = attribute value
  - message = Expected attribute value 'bar' but was 'bzz' - comparing <ns2:widget name="bar"...> at /policy[1]/widgets[1]/widget[2]/@name to <ns2:widget name="bzz"...> at /policy[1]/widgets[1]/widget[2]/@name
  - type = attribute value
  - message = Expected attribute value 'Does bar widget stuff' but was 'Does bzz widget stuff' - comparing <ns2:desc text="Does bar widget stuff"...> at /policy[1]/widgets[1]/widget[2]/desc[1]/@text to <ns2:desc text="Does bzz widget stuff"...> at /policy[1]/widgets[1]/widget[2]/desc[1]/@text
  - type = attribute value
  - message = Expected attribute value '4' but was '6' - comparing <ns2:desc version="4"...> at /policy[1]/widgets[1]/widget[2]/desc[1]/@version to <ns2:desc version="6"...> at /policy[1]/widgets[1]/widget[2]/desc[1]/@version
  - type = child
  - message = Expected child 'null' but was '{com.xyz}widget' - comparing <NULL> to <ns2:widget...> at /policy[1]/widgets[1]/widget[3]

This seems to be correctly comparing the ns2:policy line, but is incorrectly comparing the old widget 2 to the new widget 2, and indicating a new widget[3] was added.

Thanks in advance for any help you can give me.

Edit:

I found a partial answer here XMLUnit-2.0 xpath doesn't ignoring the XML node order

Diff myDiff7a = DiffBuilder.compare(myControlXML)
    .withTest(myTestXML1)
    .withNodeMatcher(new DefaultNodeMatcher(ElementSelectors.conditionalBuilder()
        .whenElementIsNamed("widget").thenUse(
            (e1, e2) -> StringUtils.equals(e1.getAttribute("name"), e2.getAttribute("name")))
        .elseUse(ElementSelectors.byName)
        .build()))
    .build();

With the 'id' attribute of the 'bar' widget modified to 21

This produces the results:

3 diffs
  - type = child nodelist sequence
  - message = Expected child nodelist sequence '1' but was '2' - comparing <ns2:widget...> at /policy[1]/widgets[1]/widget[2] to <ns2:widget...> at /policy[1]/widgets[1]/widget[3]
  - type = attribute value
  - message = Expected attribute value '19' but was '21' - comparing <ns2:widget id="19"...> at /policy[1]/widgets[1]/widget[2]/@id to <ns2:widget id="21"...> at /policy[1]/widgets[1]/widget[3]/@id
  - type = child
  - message = Expected child 'null' but was '{com.xyz}widget' - comparing <NULL> to <ns2:widget...> at /policy[1]/widgets[1]/widget[2]

This seems to correctly be saying 'widget 2 was moved to widget 3, widget 2's id changed from 19 to widget 3's id value of 21, and a new widget 2 was added.'

The only thing still missing is how to do this for arbitrary tags and attributes.

How to use XMLUnit DiffBuilder to detect differences in attributes and lists of elements

0 Answers0