Tests p:filter selects more than one thing.
Test nw-filter-004.xml is expected to pass.
<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
<p:output port="result"/>
<p:identity>
<p:with-input>
<book>
<chapter/>
<appendix/>
</book>
</p:with-input>
</p:identity>
<p:filter select="/book/*"/>
<p:wrap-sequence wrapper="wrapper"/>
</p:declare-step>
<s:schema xmlns="http://www.w3.org/1999/xhtml" xmlns:s="http://purl.oclc.org/dsdl/schematron" queryBinding="xslt2">
<s:ns prefix="c" uri="http://www.w3.org/ns/xproc-step"/>
<s:pattern>
<s:rule context="/*">
<s:assert test="self::wrapper">The result root is not wrapper.</s:assert>
<s:assert test="chapter">The wrapper doesn’t have a chapter.</s:assert>
<s:assert test="appendix">The wrapper doesn’t have an appendix.</s:assert>
</s:rule>
</s:pattern>
</s:schema>
Test p:filter