Test signal review

Review only the tests this pull request adds or grows. Tests it moves, renames, or deletes are not findings. The rules are in docs/internals/testing.md under ## What to test; read that section first and hold new tests to it.

Post each finding as a brief inline comment on the new test with one fix. Ask only for fewer or smaller tests, never for more coverage.

When there are no findings, make the entire final response exactly All clear on one line with nothing else.