Tests a p:variable does not change primary accessible port.
Test ab-variable-042.xml is expected to pass.
<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" name="pipeline" version="3.0">
<p:output port="result"/>
<p:identity name="producer">
<p:with-input>
<doc xmlns=""/>
</p:with-input>
</p:identity>
<p:variable name="prop" select="5"/>
<p:identity/>
</p:declare-step>
<s:schema xmlns:s="http://purl.oclc.org/dsdl/schematron">
<s:pattern>
<s:rule context="/">
<s:assert test="doc">The pipeline root is not doc.</s:assert>
</s:rule>
</s:pattern>
</s:schema>
Some new tests.