Task 10: TcpSource

rust crate railscale

Status

Completed 2026-03-29

What was implemented

TcpSource struct in locomotive/src/source.rs implementing the StreamSource trait from train_track.

Key details

• Wraps tokio::net::TcpListener
• bind(addr: &str) async constructor
• local_addr() helper returning SocketAddr
• accept() returns TcpStream
• StreamSource trait uses RPITIT (async fn in traits, edition 2024)
• type Error = std::io::Error (implements Into)

Files

• locomotive/src/source.rs — implementation
• locomotive/src/lib.rs — added mod source + pub use source::TcpSource
• locomotive/tests/source_test.rs — integration test

Test pattern

Binds on port 0, spawns accept task, connects TcpStream client, writes “hello”, reads it back on the server-side stream via read_exact.