Switchover testing in M-LAG environment.

Hi,
If you mean to test the master/backup switch, yes, you also should shut down the Eth-Trunk 0, so that the backup switch can be able to switch to the master role.
Actually, no matter the uplink or downlink M-LAG member interface fails(the peer-link works normally), the DFS group master and backup states do not change, in other words, though you shut down both uplink and downlink, the role switching mechanism wouldn't be triggered. To simulate that switchover, the backup switch should notice that the master device is down, in other words, the M-LAG DAD packets shouldn't be detected on the backup switch. What's more, the DAD link down but peer-link normal wouldn't cause the switchover, so you should shutdown the peer-link too.