Commit aa2846c collapsed the multi-line assert in the test-only naive
helper to a single line to drop the cold expression-arg lines that
Codecov saw as uncovered. The single-line form exceeded the 100-col
limit, so cargo fmt --check failed on every supported toolchain in CI
(ubuntu-latest, macos-latest, windows-latest).
Let rustfmt wrap it back to the three-line form. The arms are still
just a literal expression and a static-string message — no expression
format args — so the cold-path lines that Codecov originally flagged
on line 179 stay covered. No behaviour change.
kingchenc
24919153dd