Improve units tests a little bit

I am abandoning https://skia-review.googlesource.com/c/skia/+/699076 and this just salvages some of it.

Bug: skia:14298
Change-Id: I8cd85bdfb68b839a3ed72aa894f476b432de07bc
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/700397
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
2 files changed