add test for warning

src/superqt/utils/_throttler.py

@@ -29,13 +29,15 @@ SOFTWARE.
 
 from __future__ import annotations
 
-import weakref
+import warnings
 from concurrent.futures import Future
+from contextlib import suppress
 from enum import IntFlag, auto
 from functools import wraps
+from inspect import signature
 from types import MethodType
 from typing import TYPE_CHECKING, Any, Callable, Generic, TypeVar, overload
-from weakref import WeakKeyDictionary
+from weakref import WeakKeyDictionary, WeakMethod
 
 from qtpy.QtCore import QObject, Qt, QTimer, Signal
 
@@ -214,18 +216,17 @@ class QSignalDebouncer(GenericSignalThrottler):
 def _weak_func(func: Callable[P, R]) -> Callable[P, R]:
     if isinstance(func, MethodType):
         # this is a bound method, we need to avoid strong references
-        owner = func.__self__
-        class_func = func.__func__
         try:
-            instance_ref = weakref.ref(owner)
+            weak_method = WeakMethod(func)
         except TypeError as e:
             raise TypeError(REF_ERROR) from e
 
         def weak_func(*args, **kwargs):
-            if (obj := instance_ref()) is None:
-                raise RuntimeError("Method called on dead object")
-            method = class_func.__get__(obj, type(obj))
-            return method(*args, **kwargs)
+            if method := weak_method():
+                return method(*args, **kwargs)
+            warnings.warn(
+                "Method has been garbage collected", RuntimeWarning, stacklevel=2
+            )
 
         return weak_func
 
@@ -250,6 +251,9 @@ class ThrottledCallable(GenericSignalThrottler, Generic[P, R]):
             func = func.__func__
 
         max_args = get_max_args(func)
+        with suppress(TypeError, ValueError):
+            self.__signature__ = signature(func)
+
         self._func = _weak_func(func)
         self.__wrapped__ = self._func
 

tests/test_throttler.py

@@ -213,7 +213,7 @@ def test_qthrottled_does_not_prevent_gc(qtbot):
             mock()
 
         @qthrottled(timeout=1)
-        def tmethod(self) -> None:
+        def tmethod(self, x: int = 1) -> None:
             mock()
 
     thing = Thing()
@@ -225,6 +225,13 @@ def test_qthrottled_does_not_prevent_gc(qtbot):
     thing.tmethod()
     qtbot.waitUntil(thing.tmethod._future.done, timeout=2000)
     assert mock.call_count == 2
+
+    wm = thing.tmethod
+    assert isinstance(wm, ThrottledCallable)
     del thing
     gc.collect()
     assert thing_ref() is None
+
+    with pytest.warns(RuntimeWarning, match="Method has been garbage collected"):
+        wm()
+        wm._set_future_result()