Tests that XD0007 is raised if sequence arrives on a non-sequence output port.
Test ab-output-002.xml is expected to fail with error code err:XD0007.
<p:declare-step xmlns:err="http://www.w3.org/ns/xproc-error" xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
   <p:output port="result" sequence="false">
   <p:identity>
      <p:with-input>
         <doc/>
         <doc/>
      </p:with-input>
   </p:identity>
</p:declare-step>
Added new tests