The pipeline
<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" name="pipeline" version="3.0">
<p:output port="result"/>
<p:identity name="test-context">
<p:with-input>
<doc/>
</p:with-input>
</p:identity>
<p:variable name="var" select="count(collection())" collection="true">
<p:pipe step="test-context"/>
<p:inline>
<in1/>
</p:inline>
<p:pipe step="test-context"/>
<p:inline>
<in2/>
</p:inline>
<p:pipe step="test-context"/>
</p:variable>
<p:identity>
<p:with-input>
<result>{$var}</result>
</p:with-input>
</p:identity>
</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">The root element is not 'result'.</s:assert>
<s:assert test="result/text()='5'">The root element does not have a text child with '5'.</s:assert>
</s:rule>
</s:pattern>
</s:schema>
