Note: 
1. While comparison, there are some dynamic parameters. e.g. subscription id, purchase-date, expiry-date. So I add them in ignore list. 

Issue: 
1. Able to ignore xml elements like purchase-date, expiry-date while comparison. Which is fine. 
But not able to ignore attributes. e.g. for subscription, 'id' is attribute. And not able to ignore it. 

So question is hot to ignore attribute values while xml comparison. 



******This response is kept in one of the external file. This is my base file. And I compare current response against this file content*************
<response>
  <payload>
    <selfcare>
      <subscription id="2306" status="24">
          <charging-method>3</charging-method>
          <duration-code>2</duration-code>
          <rate resource="GBP" tax-rate="0.185">2.37</rate>
        </pricepoint>
        <purchase-date>2017-04-18T14:12:39+05:30</purchase-date>
        <expiry-date>2017-04-25T23:59:59+05:30</expiry-date>
        <package-id>ReservedPackage</package-id>
       <b2b-partner>
          <id>B2B_Google</id>
        </b2b-partner>
        <partner-id>B2B_Google</partner-id>
      </subscription>
    </selfcare>
  </payload>
</response>



************** This is current response ***************
<response>
  <payload>
    <selfcare>
      <subscription id="2310" status="24">
          <charging-method>3</charging-method>
          <duration-code>2</duration-code>
          <rate resource="GBP" tax-rate="0.185">2.37</rate>
        </pricepoint>
        <purchase-date>2017-04-19T14:12:39+06:30</purchase-date>
        <expiry-date>2017-04-26T23:59:59+06:30</expiry-date>
        <package-id>ReservedPackage</package-id>
       <b2b-partner>
          <id>B2B_Google</id>
        </b2b-partner>
        <partner-id>B2B_Google</partner-id>
      </subscription>
    </selfcare>
  </payload>
</response>


***********My Groovy Utility **************

import groovy.xml.XmlUtil
import org.custommonkey.xmlunit.*

def groovyUtils = new com.eviware.soapui.support.GroovyUtils( context )
def xmlParser = new XmlParser()
def writer = new StringWriter()
def writer1 = new StringWriter()
def request, response, holder, xml, p, p1, result, xmlDiff

def prefix = context.expand('${#Project#BASE_DIR}')
request = xmlParser.parse("${prefix}/API/Responses/Response_SelfFullSubs_OneSub.xml")
//request = xmlParser.parse("Responses/Response_MonetaryRefund.xml")

request = XmlUtil.serialize(request)
xml1 = xmlParser.parseText(request)

//This takes response from current API execution
holder = groovyUtils.getXmlHolder("SelfcareFullSubscriptions#Response")
response = holder.getXml()
xml = xmlParser.parseText(response)

//This parameters will be ignored while comparison      
def elelist = ["id", "purchase-date", "expiry-date"]

for (i in 0..(elelist.size())-1)
{
        varelement = elelist[i].toString()

        p = xml1.'**'."$varelement"
        p.each{ it.value = "This element is intentionally ignored for xml comparison" }

        p1 = xml.'**'."$varelement"
        p1.each{ it.value = "This element is intentionally ignored for xml comparison" }

}

new XmlNodePrinter(new PrintWriter(writer)).print(xml1)
request = writer.toString()
request = xmlParser.parseText(request)
request = XmlUtil.serialize(request)
log.info "...request... : " + request

new XmlNodePrinter(new PrintWriter(writer1)).print(xml)
result = writer1.toString()
result = xmlParser.parseText(result)
result = XmlUtil.serialize(result)
log.info "...result... : " + result

XMLUnit.setNormalizeWhitespace(true)
XMLUnit.setIgnoreWhitespace(true)
XMLUnit.setIgnoreComments(true)
XMLUnit.setIgnoreDiffBetweenTextAndCDATA(true)
XMLUnit.setNormalizeWhitespace(true)

xmlDiff = new Diff(request, result)

try{
        assert xmlDiff.identical()
} catch (Error er){
        err = er.message
        err = err.substring(err.indexOf('['))
        log.info err
        testRunner.fail("Failed comparison" + err)
} 

*********** End of Groovy Utility *****************