Error

use libtmux::ErrorKind;

let guard = libtmux::test::TestServer::new().await?;
let doomed = guard.server().new_session("doomed").await?;
let mut stale = doomed.clone();
guard.server().new_session("survivor").await?;
doomed.kill().await?;

// A handle outliving its object is the normal way this fails, so
// `is_object_gone` is the branch most callers write.
let failure = stale.rename("renamed").await.expect_err("the session is gone");
assert!(failure.is_object_gone());
assert_eq!(failure.kind(), ErrorKind::ObjectGone);

guard.shutdown().await?;