SDLC-Coverage TDD pass: peer.rs went from 74.66% → 89.04% region
coverage by adding 6 focused unit tests against the mmap variant of
SyncPeer (and its split halves):
- send/recv roundtrip on SyncPeer::Mmap
- shutdown is a no-op Ok(())
- as_stream_peer / quic_conn_clone return None for non-matching variants
- close_quic is a safe no-op for non-QUIC peers
- into_pipe_halves yields Mmap halves that roundtrip a SyncMessage
- PipeWriteHalf::shutdown and shutdown_push delegate cleanly
TCP and QUIC variants of these paths are already exercised by the
existing e2e_sync / e2e_quic_sync integration tests; the mmap variant
had zero direct unit coverage.
No production code changed; tests only.
Omar Sobh
47b90dd281