I'm trying to find a way to split the Google AppEngine for some Ip address for testing purpose is there any way to do that?
Yes, it is possible to split the incoming traffic between several GAE app/service versions based on the IP address from which the requests originate. From Splitting traffic across multiple versions:
When you have specified two or more versions for splitting, you must choose whether to split traffic by using either an IP address or HTTP cookie. It's easier to set up an IP address split, but a cookie split is more precise. For more information, see IP address splitting and Cookie splitting.
Read the respective linked section (same page) for details and limitations.
Configuring the traffic split is done from the Versions page.