The pipeline
<p:declare-step xmlns:map="http://www.w3.org/2005/xpath-functions/map" xmlns:p="http://www.w3.org/ns/xproc" name="pipeline" version="3.0">
<p:output port="result"/>
<p:cast-content-type content-type="text/html" name="caster">
<p:with-input>
<p:inline content-type="text/plain" document-properties="map{'base-uri' : 'http://xproc-test.org', 'serialization' : map{'method' : 'text'}, 'additional' : 'property'}"><html /></p:inline>
</p:with-input>
</p:cast-content-type>
<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="@caster @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:ns prefix="html" uri="http://www.w3.org/1999/xhtml"/>
<s:pattern>
<s:rule context="/">
<s:assert test="result">The root element is not result.</s:assert>
<s:assert test="result/html or result/html:html">Root element does not have a child 'html'.</s:assert>
<s:assert test="result/fn:map">Root element does not have a 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']='text/html'">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 no serialization property.</s:assert>
</s:rule>
</s:pattern>
</s:schema>
