Commit 3e0a481 made Interface mandatory for multicast in both
UDPStreamer::Initialise and UDPSServer::Initialise and updated
Docs/UDPStreamer.md, but left the GTest configs untouched. All four
multicast tests have failed since.
Add Interface to the five multicast configs. The field is parsed with
inet_addr(), so it takes a dotted-quad, not an interface name; 127.0.0.1
keeps the tests self-contained and off the LAN.
TestInitialise_MulticastMode_InvalidDataPort was passing for the wrong
reason: UDPStreamer.cpp rejected it on the missing Interface before the
DataPort == Port check could run. It now proves what its name claims.
TestExecute_MulticastConnectDataDisconnect additionally needed the
two-argument Join(): the single-argument form passes INADDR_ANY, so the
reader joined the default-route interface while the server sent on
loopback via IP_MULTICAST_IF, and the DATA datagram never arrived.
GTest: 132/132 (was 128/132), multicast subset stable over 3 runs.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
