I usually test multicast by pinging the IPv4 all-hosts multicast address:
ping 224.0.0.1
You'll see ping responses from yourself, as well as any other IPv4 hosts on your current network. Assuming they don't have firewall rules or other OS policies in place to not respond to pings or multicast pings.
By the way, if this is a wireless client, the ability to successfully send multicasts is not nearly as tricky as the ability to successfully receive multicasts. For the receive case, you'll need to perhaps ping the all-hosts multicast address from another machine on the network, and see if that other machine keeps getting ping replies from your machine.