Slowrider,  you are right about this. SnapView snapshot is need to be created on the secondary storage system for testing purpose. You can find more information on MirrorView Adapter for VMware Site Recovery Manager Release Notes  Please read "Configuring the storage for Site Recovery Manager" part on page 12 During failover testing, the MirrorView Adapter uses SnapView snapshots. When you create a SnapView snapshot of a LUN for a virtual machine, the name of the snapshot must include the following text string: VMWARE_SRM_SNAP. During failover testing, the MirrorView Adapter looks for this text string in the name of the inactive snapshot(s) for the virtual machine LUN(s) and creates a consistent snap session for this snapshot(s). When failover testing is finished, the MirrorView Adapter stops the SnapView session automatically.
Was just thinking about the process of SRM with MirrorView /S on a VNX/CX.   Would SnapView be required for a customer who wants the ability to execute a test of the recovery plan in SRM?   I'm assuming it would, since the test would leverage a writeable snapshot at the DR site.   If they never wanted to test (highly unlikely), then I'm assuming it would work without the SnapView license?
SnapView required for SRM and MirrorView