redirect based on source ip

IP::addr is a boolean operator, which you don't need to make a comparison with a data group entry. So an updated (v10/v11) version of your rule might look something like this:

when CLIENT_ACCEPTED {
     if { [class match [IP::client_addr] equals ALLOWED_IP_class] } {
          pool prodpool
     } else {
          pool testpool
     }
}

If you define ALLOWED_IP_class as an address class, then you can filter on both host (specific) and network (subnet) client IPs.