enforce multiprocessing start method spawn in test suite

Author: jakob-keller

tests/conftest.py

@@ -1,4 +1,5 @@
 import asyncio
+import multiprocessing
 import os
 import random
 import string
@@ -20,6 +21,12 @@
 _PYCHARM_HOSTED = os.environ.get('PYCHARM_HOSTED') == '1'
 
 
+@pytest.fixture(scope="session", autouse=True)
+def always_spawn():
+    # enforce multiprocessing start method `spawn` to prevent deadlocks in the child
+    multiprocessing.set_start_method("spawn", force=True)
+
+
 @pytest.fixture(
     scope="session", params=[True, False], ids=['debug[true]', 'debug[false]']
 )