Treat pytest warnings as errors

Warnings are usually a sign of something that can be improved or even
wrong, like tasks not being properly awaited or cancelled, so it's a
good idea to treat them as errors to avoid them getting unnoticed.

We still treat deprecations as warnings, as when testing with the
`pytest_min` session is normal to get deprecation warnings as we are
using old versions of dependencies.

Signed-off-by: Leandro Lucarella <luca-frequenz@llucax.com>

RELEASE_NOTES.md

@@ -10,20 +10,22 @@
 
     ```toml
     [tool.pytest.ini_options]
-    addopts = "-W=all -vv"
+    addopts = "-W=all -Werror -Wdefault::DeprecationWarning -Wdefault::PendingDeprecationWarning -vv"
     ```
 
 ### Cookiecutter template
 
-All upgrading should be done via the migration script or regenerating the templates.
+All upgrading should be done via the migration script or regenerating the templates. But you might still need to adapt your code:
+
+- `pytest` now uses `-Werror` by default (but still treat deprecations as normal warnings), so if your tests run with warnings, they will now be turned to errors, and you'll need to fix them.
 
 ## New Features
 
 <!-- Here goes the main new features and examples or instructions on how to use them -->
 
 ### Cookiecutter template
 
-<!-- Here new features for cookiecutter specifically -->
+- `pytest` now uses `-Werror -Wdefault::DeprecationWarning -Wdefault::PendingDeprecationWarning` by default. Deprecations are still treated as warnings, as when testing with the `pytest_min` session is normal to get deprecation warnings as we are using old versions of dependencies.
 
 ## Bug Fixes
 

cookiecutter/migrate.py

@@ -40,7 +40,10 @@ def add_default_pytest_options() -> None:
     pyproject_toml = Path("pyproject.toml")
     pyproject_toml_content = pyproject_toml.read_text(encoding="utf-8")
     marker = "[tool.pytest.ini_options]\n"
-    new_options = "-W=all -vv"
+    new_options = (
+        "-W=all Werror -Wdefault::DeprecationWarning "
+        "-Wdefault::PendingDeprecationWarning -vv"
+    )
 
     print(f"Adding default pytest options to {pyproject_toml}...")
     if pyproject_toml_content.find(marker) == -1:

cookiecutter/{{cookiecutter.github_repo_name}}/pyproject.toml

@@ -203,7 +203,7 @@ disable = [
 
 [tool.pytest.ini_options]
 {%- if cookiecutter.type != "api" %}
-addopts = "-W=all -vv"
+addopts = "-W=all -Werror -Wdefault::DeprecationWarning -Wdefault::PendingDeprecationWarning -vv"
 testpaths = ["tests", "src"]
 asyncio_mode = "auto"
 asyncio_default_fixture_loop_scope = "function"

pyproject.toml

@@ -205,7 +205,7 @@ module = [
 ignore_missing_imports = true
 
 [tool.pytest.ini_options]
-addopts = "-W=all -vv"
+addopts = "-W=all -Werror -Wdefault::DeprecationWarning -Wdefault::PendingDeprecationWarning -vv"
 testpaths = ["src", "tests"]
 markers = [
   "integration: integration tests (deselect with '-m \"not integration\"')",

tests_golden/integration/test_cookiecutter_generation/actor/frequenz-actor-test/pyproject.toml

@@ -153,7 +153,7 @@ disable = [
 ]
 
 [tool.pytest.ini_options]
-addopts = "-W=all -vv"
+addopts = "-W=all -Werror -vv"
 testpaths = ["tests", "src"]
 asyncio_mode = "auto"
 asyncio_default_fixture_loop_scope = "function"

tests_golden/integration/test_cookiecutter_generation/app/frequenz-app-test/pyproject.toml

@@ -152,7 +152,7 @@ disable = [
 ]
 
 [tool.pytest.ini_options]
-addopts = "-W=all -vv"
+addopts = "-W=all -Werror -vv"
 testpaths = ["tests", "src"]
 asyncio_mode = "auto"
 asyncio_default_fixture_loop_scope = "function"

tests_golden/integration/test_cookiecutter_generation/lib/frequenz-test-python/pyproject.toml

@@ -149,7 +149,7 @@ disable = [
 ]
 
 [tool.pytest.ini_options]
-addopts = "-W=all -vv"
+addopts = "-W=all -Werror -vv"
 testpaths = ["tests", "src"]
 asyncio_mode = "auto"
 asyncio_default_fixture_loop_scope = "function"

tests_golden/integration/test_cookiecutter_generation/model/frequenz-model-test/pyproject.toml

@@ -153,7 +153,7 @@ disable = [
 ]
 
 [tool.pytest.ini_options]
-addopts = "-W=all -vv"
+addopts = "-W=all -Werror -vv"
 testpaths = ["tests", "src"]
 asyncio_mode = "auto"
 asyncio_default_fixture_loop_scope = "function"