Wild card in Contains assertion

OK, I discovered that the Contains assertion uses

content.matches(replToken)

i.e. java's String.matches(String), and the default RegEx behaviour for Java is different to Groovy:

String content = '''
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" 
    xmlns:sam="http://www.soapui.org/sample/">
   <soapenv:Header/>
   <soapenv:Body>
      <sam:buyResponse>
         <sam:buyResponseContent>
            <purchasestatus>
               <rte>100</rte>
               <stockStatus>?</stockStatus>
               <expectedDelivery>?</expectedDelivery>
            </purchasestatus>
         </sam:buyResponseContent>
      </sam:buyResponse>
   </soapenv:Body>
</soapenv:Envelope>'''

String replToken = /.*rte.*/
"java: ${content.matches(replToken)}, groovy: ${(content =~ replToken).find()}"

java: false, groovy: true

The difference is in whether . matches to newline character. You can specify that it should in your Regex with (?s):

String replToken = /(?s).*rte.*/
"java: ${content.matches(replToken)}, groovy: ${(content =~ replToken).find()}"

java: true, groovy: true

Remember to write a pattern that matches to the whole response.