Add some additional sign() tests for basic unit interactions.
Bug: 40946458
Change-Id: Id29295b25fe986cfe6837519d611250ea46c3ce5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5977165
Auto-Submit: David Baron dbaron@chromium.org
Reviewed-by: Daniil Sakhapov sakhapov@chromium.org
Commit-Queue: Daniil Sakhapov sakhapov@chromium.org
Cr-Commit-Position: refs/heads/main@{#1376349}