The first fail logic seems scoped to a single test file.
Set the flag globally.
Since the tests run in a container, cleanup is automagic.
Various test tweaks to allow for skipping tests & null strings.
Use a regexp rather than a partial match to skip any DNS_CHECK_OPTIONS,
which in the current tests create whitespace, but could be anything.
Catch a missing inclusion of DNS_CHECK_OPTIONS for dig CNAME