MNT Avoid pytest warnings when pytest-run-parallel is not installed (#32088)

lesteve · web-flow · commit ad04078a22ed · 2025-09-03T09:25:29.000+02:00
diff --git a/sklearn/conftest.py b/sklearn/conftest.py
@@ -37,6 +37,14 @@
     sp_version,
 )
 
+try:
+    import pytest_run_parallel  # noqa:F401
+
+    PARALLEL_RUN_AVAILABLE = True
+except ImportError:
+    PARALLEL_RUN_AVAILABLE = False
+
+
 try:
     from scipy_doctest.conftest import dt_config
 except ModuleNotFoundError:
@@ -317,6 +325,11 @@ def pytest_generate_tests(metafunc):
         metafunc.parametrize("global_random_seed", random_seeds)
 
 
+def pytest_addoption(parser, pluginmanager):
+    if not PARALLEL_RUN_AVAILABLE:
+        parser.addini("thread_unsafe_fixtures", "list of stuff")
+
+
 def pytest_configure(config):
     # Use matplotlib agg backend during the tests including doctests
     try:
@@ -346,6 +359,25 @@ def pytest_configure(config):
         faulthandler.enable()
         faulthandler.dump_traceback_later(faulthandler_timeout, exit=True)
 
+    if not PARALLEL_RUN_AVAILABLE:
+        config.addinivalue_line(
+            "markers",
+            "parallel_threads(n): run the given test function in parallel "
+            "using `n` threads.",
+        )
+        config.addinivalue_line(
+            "markers",
+            "thread_unsafe: mark the test function as single-threaded",
+        )
+        config.addinivalue_line(
+            "markers",
+            "iterations(n): run the given test function `n` times in each thread",
+        )
+        config.addinivalue_line(
+            "markers",
+            "iterations(n): run the given test function `n` times in each thread",
+        )
+
 
 @pytest.fixture
 def hide_available_pandas(monkeypatch):
