When I set-up a MySQL HA environment for customers I usually do some final fail over tests after configuring the whole beast.
To check if the application behaves like expected I always run my little test application (test.sh) from the server(s) where the customers application runs. It displays "graphically" how the application behaves and you can show to the customer immediately what is going on...
Make sure, that you point it to the VIP (virtual IP) or the LB (load balancer).
It was really useful for me and I recommend you to do your HA fail over tests also at least with this little tool to avoid evil surprises in the future.