The pipeline
<p:declare-step xmlns:c="http://www.w3.org/ns/xproc-step" xmlns:map="http://www.w3.org/2005/xpath-functions/map" xmlns:p="http://www.w3.org/ns/xproc" xmlns:xs="http://www.w3.org/2001/XMLSchema" name="pipeline" version="3.0">
<p:output port="result"/>
<p:cast-content-type content-type="application/json" name="caster">
<p:with-input>
<p:inline document-properties="map{'base-uri' : 'http://xproc-test.org', 'serialization' : map{'indent' : true()}, 'additional' : 'property'}">
<c:param-set>
<c:param name="key" value="value"/>
</c:param-set>
</p:inline>
</p:with-input>
</p:cast-content-type>
<p:choose name="checker">
<p:when test=". instance of map(*) and map:get(., xs:QName('key')) = 'value' ">
<p:identity>
<p:with-input>
<right/>
</p:with-input>
</p:identity>
</p:when>
<p:otherwise>
<p:identity>
<p:with-input>
<wrong/>
</p:with-input>
</p:identity>
</p:otherwise>
</p:choose>
<p:cast-content-type content-type="application/xml" name="properties">
<p:with-input select="p:document-properties(.)" pipe="@caster"/>
</p:cast-content-type>
<p:wrap-sequence wrapper="result">
<p:with-input pipe="@checker @properties"/>
</p:wrap-sequence>
</p:declare-step>
Schematron validation
<s:schema xmlns:s="http://purl.oclc.org/dsdl/schematron" queryBinding="xslt2">
<s:ns prefix="fn" uri="http://www.w3.org/2005/xpath-functions"/>
<s:pattern>
<s:rule context="/">
<s:assert test="result">The root element is not result.</s:assert>
<s:assert test="result/right">Root element does not have child 'right'.</s:assert>
<s:assert test="result/fn:map">Root element does not have child 'fn:map'.</s:assert>
<s:assert test="result/fn:map/fn:string[@key='base-uri']='http://xproc-test.org'">The base-uri property is not correct.</s:assert>
<s:assert test="result/fn:map/fn:string[@key='content-type']='application/json'">The content-type property is not correct.</s:assert>
<s:assert test="result/fn:map/fn:string[@key='additional']='property'">The additional property is not correct.</s:assert>
<s:assert test="not(result/fn:map/fn:map[@key='serialization'])">There should be is no serialization property.</s:assert>
</s:rule>
</s:pattern>
</s:schema>