test: deflake recurring task test and fix tests hanging on Python 3.10

pyproject.toml

@@ -267,6 +267,11 @@ addopts = "-r a --verbose --dist worksteal"
 asyncio_default_fixture_loop_scope = "function"
 asyncio_mode = "auto"
 timeout = 1800
+# A thread timer kills the stuck worker even when its main thread is blocked and a SIGALRM handler can never run.
+timeout_method = "thread"
+# pytest-timeout writes its stack dump to the xdist worker's stdout, which never reaches the console. faulthandler
+# writes straight to the stderr file descriptor, so a test stuck this long leaves its stacks in the log.
+faulthandler_timeout = 600
 markers = [
     "run_alone: marks tests that must run in isolation",
 ]

tests/unit/_utils/test_recurring_task.py

@@ -42,18 +42,17 @@ async def test_start_and_stop(function: AsyncMock, delay: timedelta) -> None:
     assert rt.task.done()
 
 
-@pytest.mark.run_alone
 async def test_execution(function: AsyncMock, delay: timedelta) -> None:
+    """The recurring task calls its function repeatedly."""
+    third_call_done = asyncio.Event()
+    function.side_effect = lambda: third_call_done.set() if function.call_count >= 3 else None
     task = RecurringTask(function, delay)
 
     task.start()
-    await asyncio.sleep(0.2)  # Wait enough for the task to execute a few times
+    await asyncio.wait_for(third_call_done.wait(), timeout=5)
     await task.stop()
 
-    assert isinstance(task.func, AsyncMock)  # To let type checker know that the function is a mock
-    assert task.func.call_count >= 3
-
-    await task.stop()
+    assert function.call_count >= 3
 
 
 async def test_execution_continues_after_exception(delay: timedelta, caplog: pytest.LogCaptureFixture) -> None:

tests/unit/crawlers/_playwright/test_utils.py

@@ -1,3 +1,5 @@
+import sys
+
 import pytest
 from playwright.async_api import async_playwright
 from yarl import URL
@@ -65,6 +67,11 @@ async def test_infinite_scroll_no_page_without_scroll(server_url: URL) -> None:
         await browser.close()
 
 
+@pytest.mark.skipif(
+    sys.platform == 'linux' and sys.version_info < (3, 11),
+    reason='Hangs on Linux with Python 3.10: the pytest-asyncio backports runner can leak the fixture context '
+    'into the test server thread.',
+)
 async def test_double_call_infinite_scroll(server_url: URL) -> None:
     """Checks that calling infinite_scroll twice does not load more items the second time."""
     async with async_playwright() as p:

tests/unit/request_loaders/test_sitemap_request_loader.py

@@ -1,5 +1,6 @@
 import base64
 import gzip
+import sys
 from contextlib import asynccontextmanager
 from typing import TYPE_CHECKING, Any, cast
 from unittest.mock import AsyncMock, MagicMock, patch
@@ -346,6 +347,11 @@ def transform_request(request_options: RequestOptions) -> RequestOptions | Reque
     assert extracted_urls == get_basic_results(server_url)
 
 
+@pytest.mark.skipif(
+    sys.platform == 'linux' and sys.version_info < (3, 11),
+    reason='Hangs on Linux with Python 3.10: the pytest-asyncio backports runner can leak the fixture context '
+    'into the test server thread.',
+)
 async def test_transform_request_function_with_skip(server_url: URL, http_client: HttpClient) -> None:
     sitemap_url = (server_url / 'sitemap.xml').with_query(
         base64=encode_base64(get_basic_sitemap(url=server_url).encode())