Context
From the first full mutation-testing run (ADR-007 workflow, 2026-07-04, partial). Survivors in <impl AsyncRead for RewindStream<S>>::poll_read in src/rewind_stream.rs.
Surviving mutants
src/rewind_stream.rs:72 — < with == / < with > / < with <=, > with ==, || with &&src/rewind_stream.rs:77 — >= with <, && with ||, delete !
Analysis
The only direct unit test covers the invalid-leftover-bounds error path. The replay-then-inner path is exercised indirectly (client/server leftover handling), almost always with empty leftover, which skips both mutated branches. No test asserts correct byte delivery when the read buffer is smaller than the buffered leftover (to_copy < remaining).
Suggested test
Unit-test RewindStream with non-empty leftover and a ReadBuf smaller than the leftover: poll repeatedly and assert the exact bytes and ordering across the split, followed by bytes from the inner stream.
Context
From the first full mutation-testing run (ADR-007 workflow, 2026-07-04, partial). Survivors in
<impl AsyncRead for RewindStream<S>>::poll_readinsrc/rewind_stream.rs.Surviving mutants
src/rewind_stream.rs:72—< with ==/< with >/< with <=,> with ==,|| with &&src/rewind_stream.rs:77—>= with <,&& with ||,delete !Analysis
The only direct unit test covers the invalid-leftover-bounds error path. The replay-then-inner path is exercised indirectly (client/server leftover handling), almost always with empty leftover, which skips both mutated branches. No test asserts correct byte delivery when the read buffer is smaller than the buffered leftover (
to_copy < remaining).Suggested test
Unit-test
RewindStreamwith non-empty leftover and aReadBufsmaller than the leftover: poll repeatedly and assert the exact bytes and ordering across the split, followed by bytes from the inner stream.