Shard 0 of the nightly mutation run reported two MISSED mutants:
src/builder.rs:178 Builder::failure_retry_period -> Self
src/builder.rs:210 Builder::dht_backend -> Self
Both replaced the setter body with `Default::default()`, wiping the
receiver's accumulated state. The existing #[cfg(test)] mod tests has
one of these `<setter>_setter_stores_exact_value` pinning tests for
nearly every other Builder method, but these two were missing:
- failure_retry_period: no test exercised the setter at all.
- dht_backend: the method and its callers (build_wait_none_does_not_block
et al.) are gated `#[cfg(feature = "test-support")]`, but
cargo-mutants ran with default features only, so neither the method
nor its tests were ever compiled — the mutation survived trivially.
Fixes:
- Add `failure_retry_period_setter_stores_exact_value` matching the
pattern of the other setter tests.
- Add `dht_backend_setter_stores_value` (gated on `test-support`).
- Set `additional_cargo_args = ["--features", "test-support"]` in
.cargo/mutants.toml so cfg-gated setters are part of the mutation
surface.
Verified locally: `cargo mutants --file src/builder.rs` → 17 mutants,
16 caught, 1 unviable, 0 missed.
swaits
312d958a91