Avoid reading platform specific `/etc/resolv.conf` in `TestDNSResolver`
unit tests. Systems (e.g. sandboxes) may not have `/etc/resolv.conf`
or this file may not contain any configured name servers.
`TestDNSResolver` unit tests check only customized `nameservers`
property and should not depend on existence of `/etc/resolv.conf`.
Resolver accepts `configure` option.
https://dnspython.readthedocs.io/en/latest/resolver-class.html :
> configure, a bool. If True (the default), the resolver instance is
configured in the normal fashion for the operating system the resolver
is running on. (I.e. by reading a /etc/resolv.conf file on POSIX
systems and from the registry on Windows systems.)
Fixes: https://pagure.io/freeipa/issue/9319
Signed-off-by: Stanislav Levin <slev@altlinux.org>
Reviewed-By: Florence Blanc-Renaud <flo@redhat.com>
Stanislav Levin
2996cc8eae