Hello,
Well, for an XML response you could match the content of a specific element against a regular expression perhaps?
In the Outline view showing the response, right-click the desired element, and select "Add Assertion..." "for Content matching RegEx". When prompted to specify a regular expression to match against, you can use ".*\n.*" (without the quotes) to match some text containing a newline character. The expected result should be "true". The generated expression should be simmilar to this:
declare namespace sam='http://www.soapui.org/sample/';
matches( //sam:loginResponse[1]/sessionid[1]/text(), '.*\n.*' )
Regards,
Dain
eviware.com