Log the number of xdist workers in pytest runs (#183682)

Co-authored-by: epenet <6771947+epenet@users.noreply.github.com>

tests/conftest.py

@@ -1,7 +1,7 @@
 """Set up some common test helper things."""
 
 import asyncio
-from collections.abc import AsyncGenerator, Callable, Coroutine, Generator
+from collections.abc import AsyncGenerator, Callable, Coroutine, Generator, Sequence
 from contextlib import AsyncExitStack, asynccontextmanager, contextmanager
 import datetime
 import functools
@@ -33,6 +33,7 @@ from aiohttp.typedefs import JSONDecoder
 from aiohttp.web import Application
 import bcrypt
 from bleak_retry_connector import bleak_manager
+import execnet
 import freezegun
 import multidict
 import pytest
@@ -177,6 +178,15 @@ def pytest_configure(config: pytest.Config) -> None:
         logging.getLogger().setLevel(logging.DEBUG)
 
 
+@pytest.hookimpl(optionalhook=True)
+def pytest_xdist_setupnodes(
+    config: pytest.Config, specs: Sequence[execnet.XSpec]
+) -> None:
+    """Log the number of xdist workers, also when running with -qq."""
+    if reporter := config.pluginmanager.get_plugin("terminalreporter"):
+        reporter.write_line(f"xdist workers: {len(specs)}")
+
+
 class HASocketBlockedError(pytest_socket.SocketBlockedError):
     """SocketBlockedError variant which counts instances."""