how to test HA with VMWare VSA ESXi v5.1

If you have a VMware HA cluster, all VMs in the Cluster are protected by HA.

As for test, just remove the power on one of your hosts, make sure it's an un-controlled shutdown.

Controlled Shutdowns, e.g. Shutdown from the Menu, are not host failures, so you need to create a host failure.

Have only one VM  (non-production) running on the server and what you need to do is either shutoff power or reset the machine.  Your VM should boot up on one of the other hosts in the cluster.

Resetting the Host is not a host failure.

I'm not sure to how I feel pulling the power on one of my hosts... I thought there was a command you could send to a host to emulate a mainboard failure...

Also,

As I understand all data is mirrored.  Where can I see the mirror copy?

That's how you test it.

Data is mirrored in the VSA Cluster.

How do you see the mirrored version?   When browsing the datastores I don't see the production/working folder of the VM.

That's correct. VSA Management tools, should show Cluster status.

the VSA cluster node1 (LUN) is mirrored onto the other VSA cluster node2 (internally).

Only one LUN (datastore) is mapped to the Hosts via the single cluster IP Address.

It's a background task which is mirroring and replicating between VSA nodes.

Turn off a node, and the VMs should still be up.

When you say turn off a node.  Are you referring to pulling the power on a ESXi host cluster member or one of the VSA nodes??