fix test_default_executor

adaptive/runner.py

@@ -49,6 +49,11 @@
     asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
 
 
+_default_executor = (
+    loky.get_reusable_executor if with_loky else concurrent.ProcessPoolExecutor
+)
+
+
 class BaseRunner(metaclass=abc.ABCMeta):
     r"""Base class for runners that use `concurrent.futures.Executors`.
 
@@ -478,7 +483,11 @@ def __init__(
             def goal(_):
                 return False
 
-        if executor is None and not inspect.iscoroutinefunction(learner.function):
+        if (
+            executor is None
+            and _default_executor is concurrent.ProcessPoolExecutor
+            and not inspect.iscoroutinefunction(learner.function)
+        ):
             try:
                 pickle.dumps(learner.function)
             except pickle.PicklingError:
@@ -756,13 +765,6 @@ def shutdown(self, wait=True):
         pass
 
 
-def _default_executor():
-    if with_loky:
-        return loky.get_reusable_executor()
-    else:
-        return concurrent.ProcessPoolExecutor()
-
-
 def _ensure_executor(executor):
     if executor is None:
         executor = _default_executor()