Tests that err:XS0015 is raised.
Test nw-err-xs0015-003.xml is expected to fail with error code err:XS0015.
<p:declare-step xmlns:err="http://www.w3.org/ns/xproc-error" xmlns:ex="http://test" xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
<p:output port="result"/>
<p:group/>
</p:declare-step>
Initial commit.