This page contains guidelines on where to put configuration for testing. NOT configuration for aiosmtpd itself.

1. pyproject.toml

   Some packages may require specifying an [extra] flag, e.g., coverage[toml].

2. setup.cfg

   For example, pytype and flake8 does not (yet) support pyproject.toml

3. tox.ini if still exists

   tox is capable of reading its .ini from pyproject.toml. So, this file must always be low in the order of precedence, because it might disappear in the future.

4. Tool's own config file / custom config file

   For example, bandit has no default config file. One must create a config file for this tool to run. And not only the config is YAML (so incompatible with the 3 files above), sticking it inside an unrelated config file will cause errors.

   So, in similar situations, we should create the tool's own config file.

   This also applies to "external" tools such as lgtm.yml, readthedocs.yml, etc.