check open processes in test

tests/conftest.py

@@ -0,0 +1,21 @@
+
+import psutil
+import os
+import pytest
+
+@pytest.fixture(autouse=True)
+def check_subprocesses():
+    # Get a list of child PIDs before the test starts
+    parent = psutil.Process(os.getpid())
+    before_children = {child.pid for child in parent.children(recursive=True)}
+
+    yield
+
+    after_children = {child.pid for child in parent.children(recursive=True)}
+    leftover_processes = after_children - before_children
+
+    if leftover_processes:
+        leftover_details = [
+            f"PID {p.pid}: {p.cmdline()}" for p in parent.children(recursive=True) if p.pid in leftover_processes
+        ]
+        pytest.fail(f"Lingering subprocesses detected:\n" + "\n".join(leftover_details))