feat!: Remove legacy mode. (#414)

Asyncio modes have been introduced in v0.17.0 which was released on 2022-01-13. In addition to the auto and strict modes, the release defaulted to "legacy" mode for backwards compatibility. The release also issued a deprecation warning when using legacy mode.

The default asyncio mode was changed to _strict_ in the v0.19.0 release on 2022-07-13.

This change removes legacy mode entirely.

Signed-off-by: Michael Seifert <m.seifert@digitalernachschub.de>

Author: seifertm

CHANGELOG.rst

@@ -4,6 +4,7 @@ Changelog
 
 UNRELEASED
 =================
+- BREAKING: Removed *legacy* mode. If you're upgrading from v0.19 and you haven't configured ``asyncio_mode = legacy``, you can upgrade without taking any additional action. If you're upgrading from an earlier version or you have explicitly enabled *legacy* mode, you need to switch to *auto* or *strict* mode before upgrading to this version.
 - Fixed an issue which prevented fixture setup from being cached. `#404 <https://github.com/pytest-dev/pytest-asyncio/pull/404>`_
 
 0.19.0 (22-07-13)

README.rst

@@ -57,8 +57,7 @@ This is enough for pytest to pick up pytest-asyncio.
 Modes
 -----
 
-Starting from ``pytest-asyncio>=0.17``, three modes are provided: *auto*, *strict* and
-*legacy*. Starting from ``pytest-asyncio>=0.19`` the *strict* mode is the default.
+Pytest-asyncio provides two modes: *auto* and *strict* with *strict* mode being the default.
 
 The mode can be set by ``asyncio_mode`` configuration option in `configuration file
 <https://docs.pytest.org/en/latest/reference/customize.html>`_:
@@ -107,18 +106,6 @@ suite.
 This mode is used by default for the sake of project inter-compatibility.
 
 
-Legacy mode
-~~~~~~~~~~~
-
-This mode follows rules used by ``pytest-asyncio<0.17``: tests are not auto-marked but
-fixtures are.
-
-Deprecation warnings are emitted with suggestion to either switching to ``auto`` mode
-or using ``strict`` mode with ``@pytest_asyncio.fixture`` decorators.
-
-The default was changed to ``strict`` in ``pytest-asyncio>=0.19``.
-
-
 Fixtures
 --------
 
@@ -204,7 +191,7 @@ to redefine the ``event_loop`` fixture to have the same or broader scope.
 Async fixtures need the event loop, and so must have the same or narrower scope
 than the ``event_loop`` fixture.
 
-*auto* and *legacy* mode automatically converts async fixtures declared with the
+*auto* mode automatically converts async fixtures declared with the
 standard ``@pytest.fixture`` decorator to *asyncio-driven* versions.
 
 

pytest_asyncio/plugin.py

@@ -6,7 +6,6 @@
 import inspect
 import socket
 import sys
-import warnings
 from typing import (
     Any,
     AsyncIterator,
@@ -55,31 +54,13 @@
 class Mode(str, enum.Enum):
     AUTO = "auto"
     STRICT = "strict"
-    LEGACY = "legacy"
-
-
-LEGACY_MODE = DeprecationWarning(
-    "The 'asyncio_mode' default value will change to 'strict' in future, "
-    "please explicitly use 'asyncio_mode=strict' or 'asyncio_mode=auto' "
-    "in pytest configuration file."
-)
-
-LEGACY_ASYNCIO_FIXTURE = (
-    "'@pytest.fixture' is applied to {name} "
-    "in 'legacy' mode, "
-    "please replace it with '@pytest_asyncio.fixture' as a preparation "
-    "for switching to 'strict' mode (or use 'auto' mode to seamlessly handle "
-    "all these fixtures as asyncio-driven)."
-)
 
 
 ASYNCIO_MODE_HELP = """\
 'auto' - for automatically handling all async functions by the plugin
 'strict' - for autoprocessing disabling (useful if different async frameworks \
 should be tested together, e.g. \
 both pytest-asyncio and pytest-trio are used in the same project)
-'legacy' - for keeping compatibility with pytest-asyncio<0.17: \
-auto-handling is disabled but pytest_asyncio.fixture usage is not enforced
 """
 
 
@@ -187,8 +168,6 @@ def pytest_configure(config: Config) -> None:
         "mark the test as a coroutine, it will be "
         "run using an asyncio event loop",
     )
-    if _get_asyncio_mode(config) == Mode.LEGACY:
-        config.issue_config_time_warning(LEGACY_MODE, stacklevel=2)
 
 
 @pytest.mark.tryfirst
@@ -217,20 +196,6 @@ def _preprocess_async_fixtures(config: Config, holder: Set[FixtureDef]) -> None:
                 elif asyncio_mode == Mode.AUTO:
                     # Enforce asyncio mode if 'auto'
                     _set_explicit_asyncio_mark(func)
-                elif asyncio_mode == Mode.LEGACY:
-                    _set_explicit_asyncio_mark(func)
-                    try:
-                        code = func.__code__
-                    except AttributeError:
-                        code = func.__func__.__code__
-                    name = (
-                        f"<fixture {func.__qualname__}, file={code.co_filename}, "
-                        f"line={code.co_firstlineno}>"
-                    )
-                    warnings.warn(
-                        LEGACY_ASYNCIO_FIXTURE.format(name=name),
-                        DeprecationWarning,
-                    )
 
             to_add = []
             for name in ("request", "event_loop"):

tests/modes/test_legacy_mode.py

@@ -42,7 +42,7 @@ async def test_fixture_with_params(fixture_with_params):
     assert fixture_with_params % 2 == 0
 
 
-@pytest.mark.parametrize("mode", ("auto", "strict", "legacy"))
+@pytest.mark.parametrize("mode", ("auto", "strict"))
 def test_sync_function_uses_async_fixture(testdir, mode):
     testdir.makepyfile(
         dedent(