test: opt rollingops and nginx_k8s in to warnings-as-errors

nginx_k8s/CHANGELOG.md

@@ -1,6 +1,7 @@
 # Unreleased
 
 - Updated project URLs.
+- Close the config file that `_has_config_changed` pulls from the container, instead of leaving it to the garbage collector.
 
 # 1.0.1 - 22 June 2026
 

nginx_k8s/src/charmlibs/nginx_k8s/_nginx.py

@@ -165,8 +165,11 @@ def _has_config_changed(self, new_config: str) -> bool:
             return False
 
         try:
-            with _tracer.start_as_current_span('read config'):
-                current_config = self._container.pull(self.NGINX_CONFIG).read()
+            with (
+                _tracer.start_as_current_span('read config'),
+                self._container.pull(self.NGINX_CONFIG) as config_file,
+            ):
+                current_config = config_file.read()
         except pebble.PathError:
             logger.debug('nginx configuration file not found at %s', str(self.NGINX_CONFIG))
             # file does not exist! it's probably because it's the first time we're generating it.

nginx_k8s/tests/conftest.py

@@ -0,0 +1,21 @@
+# Copyright 2026 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+"""Pytest configuration and fixtures that apply to all this package's tests."""
+
+import pytest
+
+
+def pytest_configure(config: pytest.Config) -> None:
+    """Pytest configuration specific to the nginx_k8s package.
+
+    Used instead of the package's ``pyproject.toml`` or ``pytest.ini`` so that the repository
+    root's ``pyproject.toml`` is treated as the pytest root. Otherwise pytest would use the
+    package's file as its only config, silently dropping the root's ``--strict-markers`` and
+    shared marker list.
+    """
+    # Opt in to warnings-as-errors.
+    # Relax a category for a single test with the @pytest.mark.filterwarnings decorator:
+    # https://docs.pytest.org/en/stable/reference/reference.html#pytest-mark-filterwarnings-ref
+    # https://docs.python.org/3/library/warnings.html#warning-filter
+    config.addinivalue_line('filterwarnings', 'error')

rollingops/tests/conftest.py

@@ -0,0 +1,21 @@
+# Copyright 2026 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+"""Pytest configuration and fixtures that apply to all this package's tests."""
+
+import pytest
+
+
+def pytest_configure(config: pytest.Config) -> None:
+    """Pytest configuration specific to the rollingops package.
+
+    Used instead of the package's ``pyproject.toml`` or ``pytest.ini`` so that the repository
+    root's ``pyproject.toml`` is treated as the pytest root. Otherwise pytest would use the
+    package's file as its only config, silently dropping the root's ``--strict-markers`` and
+    shared marker list.
+    """
+    # Opt in to warnings-as-errors.
+    # Relax a category for a single test with the @pytest.mark.filterwarnings decorator:
+    # https://docs.pytest.org/en/stable/reference/reference.html#pytest-mark-filterwarnings-ref
+    # https://docs.python.org/3/library/warnings.html#warning-filter
+    config.addinivalue_line('filterwarnings', 'error')