Restore implicit switch to asyncio_mode = auto if legacy mode is detected

Author: asvetlov

CHANGES.rst

@@ -1,6 +1,11 @@
 CHANGES
 =======
 
+1.0.2 (2022-01-20)
+------------------
+
+- Restore implicit switch to ``asyncio_mode = auto`` if *legacy* mode is detected.
+
 1.0.1 (2022-01-20)
 ------------------
 

pytest_aiohttp/plugin.py

@@ -10,6 +10,24 @@
 AiohttpClient = Callable[[Union[Application, BaseTestServer]], Awaitable[TestClient]]
 
 
+LEGACY_MODE = DeprecationWarning(
+    "The 'asyncio_mode' is 'legacy', switching to 'auto' for the sake of "
+    "pytest-aiohttp backward compatibility. "
+    "Please explicitly use 'asyncio_mode=strict' or 'asyncio_mode=auto' "
+    "in pytest configuration file."
+)
+
+
+@pytest.mark.tryfirst
+def pytest_configure(config) -> None:
+    val = config.getoption("asyncio_mode")
+    if val is None:
+        val = config.getini("asyncio_mode")
+    if val == "legacy":
+        config.option.asyncio_mode = "auto"
+        config.issue_config_time_warning(LEGACY_MODE, stacklevel=2)
+
+
 @pytest.fixture
 def loop(event_loop: asyncio.AbstractEventLoop) -> asyncio.AbstractEventLoop:
     warnings.warn(

tests/test_switch_mode.py

@@ -0,0 +1,48 @@
+from typing import Any
+
+from pytest_aiohttp.plugin import LEGACY_MODE
+
+pytest_plugins: str = "pytester"
+
+
+def test_warning_for_legacy_mode(testdir: Any) -> None:
+    testdir.makepyfile(
+        """\
+async def test_a():
+    pass
+
+"""
+    )
+    result = testdir.runpytest_subprocess("--asyncio-mode=legacy")
+    result.assert_outcomes(passed=1)
+    result.stdout.fnmatch_lines(["*" + str(LEGACY_MODE) + "*"])
+
+
+def test_auto_mode(testdir: Any) -> None:
+    testdir.makepyfile(
+        """\
+async def test_a():
+    pass
+
+"""
+    )
+    result = testdir.runpytest_subprocess("--asyncio-mode=auto")
+    result.assert_outcomes(passed=1)
+    result.stdout.no_fnmatch_line("*" + str(LEGACY_MODE) + "*")
+
+
+def test_strict_mode(testdir: Any) -> None:
+    testdir.makepyfile(
+        """\
+import pytest
+
+
+@pytest.mark.asyncio
+async def test_a():
+    pass
+
+"""
+    )
+    result = testdir.runpytest_subprocess("--asyncio-mode=strict")
+    result.assert_outcomes(passed=1)
+    result.stdout.no_fnmatch_line("*" + str(LEGACY_MODE) + "*")