Tests p:step-available with use-when and a chain of hidden steps.
If the use of step-available on p:import is treated as a special case,
this ends in failure. But an argument could be made that this contains
a deadlock.
The pipeline
<p:declare-step xmlns:ex="http://extension" xmlns:imp="http://example.com/steps" xmlns:p="http://www.w3.org/ns/xproc" name="main" version="3.0">
<p:import href="../pipelines/nw-decl1.xpl" use-when="p:step-available('imp:step2')"/>
<p:import href="../pipelines/nw-decl2.xpl" use-when="p:step-available('imp:step3')"/>
<p:import href="../pipelines/nw-decl3.xpl" use-when="p:step-available('imp:step1')"/>
<p:output port="result"/>
<p:identity>
<p:with-input>
<result>
<test>{p:step-available('imp:step1')}</test>
</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 document root is not “result”.</s:assert>
<s:assert test="result/test/text()='false'">p:step-available for 'imp:step1' is wrong.</s:assert>
</s:rule>
</s:pattern>
</s:schema>
