test: make more stable by waiting for task to finish

tests/integration/memleak_test.py

@@ -1,4 +1,5 @@
 import gc
+import threading
 import time
 import weakref
 from pathlib import Path
@@ -45,6 +46,11 @@ def _scoped_test_memleak(
  shell = weakref.ref(kernel().shell)
  session = weakref.ref(kernel().session)
  page_session.goto("about:blank")
+ if context()._last_kernel_cull_task:
+ if not context()._last_kernel_cull_task.done():
+ event = threading.Event()
+ context()._last_kernel_cull_task.add_done_callback(lambda _: event.set())
+ assert event.wait()
  assert context().closed_event.wait(10)
  if shell():
  del shell().__dict__