The pipeline
<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
<p:output port="result"/>
<p:identity>
<p:with-input>
<doc>
<value>5</value>
</doc>
</p:with-input>
</p:identity>
<p:choose>
<p:when test="/doc/value/text() != '5'">
<p:identity>
<p:with-input>
<wrong-result/>
</p:with-input>
</p:identity>
</p:when>
<p:otherwise>
<p:identity>
<p:with-input>
<result>{/doc/value/text()}</result>
</p:with-input>
</p:identity>
</p:otherwise>
</p:choose>
</p:declare-step>
Schematron validation
<s:schema xmlns="http://www.w3.org/1999/xhtml" xmlns:s="http://purl.oclc.org/dsdl/schematron" queryBinding="xslt2">
<s:pattern>
<s:rule context="/">
<s:assert test="/result">Document root is not named 'result'.</s:assert>
<s:assert test="count(*) = 1">Document does not have exactly one child element.</s:assert>
<s:assert test="/result/text()='5'">Element 'result' does not have a text child with '5'.</s:assert>
</s:rule>
</s:pattern>
</s:schema>
