shard_read_costs_for_empty_disk_set_are_empty was a plain sync #[test], but
shard_read_costs_for_disks consults process-global topology state
(local_endpoint_hosts_for_shard_costs) whose fast-lock manager lazily spawns a
background cleanup task on first access. When this test was the first in a
process to touch that global — as under nextest's per-test isolation — the
tokio::spawn panicked with a TryCurrentError because no runtime was present,
making the test order-dependent flaky in CI (it passes only when some sibling
tokio test initializes the manager first).
Run it under a Tokio runtime like the sibling reservation tests
(#[tokio::test]), so the lazy init's spawn always has a runtime. Test-only
change; no production behavior change.
Verified failing before the change and passing after under both
`cargo test` and `cargo nextest run` in isolation.
Co-authored-by: heihutu <heihutu@gmail.com>
houseme
7048a9a3ed