You're taking it up one level, so extrapolate the argument solution up one level - use a hash of arrays or an array of arrays:

my %functions = (
  function1 => {arglist1 => ["arg1", { arg2 => val2 }],
                arglist2 => [...],
                ...
               },
  function2 => {...},
  ...,
);


while (my ($func, $argsList) = each %functions) {
    for my $key (keys %$argsList) {
        print "Test $func against args $key\n"
        &{"harcommon::$func"}(@{$argsList->{$key}});
    }
}
[download]

or:

my %functions = (
  function1 => [["arg1", { arg2 => val2 }],
                [...],
                ...
               ],
  function2 => [...],
  ...,
);


while (my ($func, $argsList) = each %functions) {
    for my $args (@$argsList) {
        print "Test $func against args $key\n"
        &{"harcommon::$func"}(@$args);
    }
}
[download]