Try this

Author: jrfnl

tests/Core/Ruleset/ExpandRulesetReferenceTest.xml

@@ -1,6 +1,8 @@
 <?xml version="1.0"?>
 <ruleset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="ExpandRulesetReferenceTest" xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/PHPCSStandards/PHP_CodeSniffer/master/phpcs.xsd">
 
+    <config name="installed_paths" value="./tests/Core/Ruleset/Fixtures/TestStandard/"/>
+
     <!-- LINE 993-994 ?? test ONLINE Including a category of sniffs via a ruleset relative directory ref. -->
     <rule ref="./fixtures/teststandard/sniffs/validsniffs"/>