The MVP pass criteria include ARP from the Windows TAP side to a LAN host. The
real-session relay integration tests proved generic Ethernet forwarding, but
that did not explicitly exercise ARP-shaped traffic.
Add a real client/relay/gateway session test that sends an ARP request-shaped
broadcast frame from the client to the gateway and an ARP reply-shaped unicast
frame from the gateway back to the client. The test keeps the proof at the L2
boundary while staying independent of a real Windows TAP adapter or LAN host.
Test Plan:
- cargo fmt --check
- cargo test -p lanparty-relay \
bridges_arp_frames_between_client_and_gateway_sessions -- --nocapture
- cargo test -p lanparty-relay
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings
- git diff --check
Refs: MVP ARP pass condition
ddidderr
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