Test PHP application for IPv6 compatibility

[kittykitty]

 I have an existing php website application. I'm on IPv4, how can I fake IPv6 address to test the application compatibility with it? or is there a better way to test IPv6 compatibility?
I need to be sure my application compatibility with IPv6 is ready for production on both IPv4 networks + IPv6 networks.

[kasperd]

or is there a better way to test IPv6 compatibility?

Deploy IPv6 in your test environment (using a tunnel if there is currently no other way to get IPv6 in your test environment).