<phpunit backupGlobals="true">
    <testsuite>
        <directory>./tests</directory>
    </testsuite>
</phpunit>

<phpunit backupGlobals="true">
    <testsuite>
        <directory suffix='.hh'>./tests</directory>
</phpunit>

Add suffix attribute to search for hh files
Add suffix attribute to search for hh files