🧪 Make pytest notify us about future warnings

In essence, this configures Python to turn any warnings emitted in
runtime into errors[[1]]. This is the best practice that allows
reacting to future deprecation announcements that are coming from the
dependencies (direct, or transitive, or even CPython itself)[[2]].

The typical workflow looks like this:

  1. If a dependency is updated an a warning is hit in tests, the
     deprecated thing should be replaced with newer APIs.

  2. If a dependency is transitive or we have no control over it
     otherwise, the specific warning and a regex matching its message,
     plus the module reference (where possible) can be added to the
     list of temporary ignores in `pytest.ini`.

  3. The list of temporary ignores should be reevaluated periodically,
     including when dependency re-pinning in lockfile is happening.

[1]: https://docs.python.org/3/using/cmdline.html#cmdoption-W
[2]: https://pytest-with-eric.com/configuration/pytest-ignore-warnings/

awxkit/tox.ini

@@ -44,4 +44,8 @@ max-line-length = 120
 
 [pytest]
 addopts = -v --tb=native
+
+filterwarnings =
+  error
+
 junit_family=xunit2

pytest.ini

@@ -12,6 +12,9 @@ markers =
     job_runtime_vars:
     fixture_args:
 
+filterwarnings =
+  error
+
 # https://docs.pytest.org/en/stable/usage.html#creating-junitxml-format-files
 junit_duration_report = call
 # xunit1 contains more metadata than xunit2 so it's better for CI UIs: