foreach my $num ( $point->coordinates ) {
    ok looks_like_number($num), "... and $num should be a number";
}

##</code><code>##

ok my @coordinates = $point->coordinates, 
  'coordinates() should return the coordinates';
is scalar @coordinates, 3, '... and it should return the correct number of them';
foreach my $num ( @coordinates ) {
    ok looks_like_number($num), "... and each should be a number ($num)";
}