I wonder if a better assertion could be used in this test?  Perhaps <assert-count>1</assert-count>?

   <test-case name="K2-OrderbyExprWithout-42">
      <description> Apply fn:string() on a for clause that only produces on item, and that cannot easily constant propagate. </description>
      <created by="Frans Englich" on="2007-11-26"/>
      <test>string(for $i in current-date() order by $i return $i)</test>
      <result>
         <assert>true()</assert>
      </result>
   </test-case>