[automerger skipped] Improve test coverage for FakeValueGenerator. am: 83fe805275 am: 7f6fa2e136 -s ours

am skip reason: Merged-In I6df508e148ff0348fc28b467b4e5a70cf5727a27 with SHA-1 83fe805275 is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/hardware/interfaces/+/16997312

Change-Id: I6b475407d2de204c988ba63883522221743cf0f0