Putting t.Parallel() in each test makes them run in parallel.
Additional t.Parallel() could be added to each subtest, although
that requires making a local copy of the loop variable for
table driven tests.
Test: m checkbuild
Change-Id: I5d9869ead441093f4d7c5757f2447385333a95a4
Some of the warnings are too common to fix/opt-out for non-Google
projects.
Also in the change, minor clean up of duplicated code.
Test: presubmit
Bug: 139945549
Change-Id: Ic176ef1f17133405851a79592b6bef5ccb403bd9