%test:args with string containing a comma

Is it possible to pass a string value to %test:args() (or %test:arg()) that contains a comma?  For example,

declare
    %test:args("0.0.0.1, 0.0.0.2")
        %test:assertEquals("0.0.0.1")
function spasexq:getHttpClient(
    $fwdForHdr as xs:string*)
as xs:string
{
    let $hops := if (count($fwdForHdr) > 0)
                then tokenize($fwdForHdr[1], ", ")
                else ()
    return
        if ($hops)
        then
            $hops[1]
        else
            "unknown"
};

The test case fails with

        <testcase name="getHttpClient" class="spasexq:getHttpClient">
            <error type="err:FORG0006" message="Invalid argument type. effectiveBooleanValue: first item of '(0.0.0.1, 0.0.0.2)' is not a node, and sequence length &gt; 1"/>
        </testcase>

Is there an escape mechanism to prevent the interpretation of the comma character?  All my attempts have failed.  Thanks.

Bernie Harris