Enforcing pylint standards and default for our test code seems
counter-productive. Since most of the newly added code are tests or is
test-related, encountering these checks rarely make us refactor the code
in other ways and we just disable these checks individually. Code that
is too complex or convoluted will be pointed out in reviews anyways.
Implement a new Python class, AsyncDnsServer, which can be used by
ans.py scripts placed in ansX/ system test subdirectories. This enables
conveniently starting a feature-limited, non-standards-compliant, custom
DNS server instance. It can read and serve zone files, but it is also
able to evaluate any user-provided query-processing logic, allowing
query responses to be changed, delayed, or dropped altogether. These
are all actions commonly taken by custom DNS servers written in Python
that are used in BIND 9 system tests. Having a single "base"
implementation of such a custom DNS server reduces code duplication,
improving test maintainability.
Co-authored-by: Tom Krizek <tkrizek@isc.org>
