From 2fe82b2fdf94e0b17747a30a05b63d830cd7d790 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rgrossekunst@nvidia.com>
Date: Sat, 19 Apr 2025 00:18:23 -0700
Subject: [PATCH] [skip ci] Simplify test case.

---
 tests/test_class_sh_trampoline_weak_ptr.cpp | 64 +++++++++------------
 tests/test_class_sh_trampoline_weak_ptr.py  | 35 +++++------
 2 files changed, 40 insertions(+), 59 deletions(-)

diff --git a/tests/test_class_sh_trampoline_weak_ptr.cpp b/tests/test_class_sh_trampoline_weak_ptr.cpp
index dd53206e4..9b7651cce 100644
--- a/tests/test_class_sh_trampoline_weak_ptr.cpp
+++ b/tests/test_class_sh_trampoline_weak_ptr.cpp
@@ -1,41 +1,37 @@
-// Copyright (c) 2021 The Pybind Development Team.
+// Copyright (c) 2025 The Pybind Development Team.
 // All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "pybind11_tests.h"
 
-#include <utility>
+#include <memory>
 
 namespace pybind11_tests {
 namespace class_sh_trampoline_weak_ptr {
 
-// // For testing whether a python subclass of a C++ object can be accessed from a C++ weak_ptr
-struct WpBase {
-    // returns true if the base virtual function is called
-    virtual bool is_base_used() { return true; }
+struct VirtBase {
+    virtual ~VirtBase() = default;
+    virtual int get_code() { return 100; }
+};
 
-    // returns true if there's an associated python instance
-    bool has_python_instance() {
-        auto *tinfo = py::detail::get_type_info(typeid(WpBase));
-        return (bool) py::detail::get_object_handle(this, tinfo);
+struct PyVirtBase : VirtBase, py::trampoline_self_life_support {
+    using VirtBase::VirtBase;
+    int get_code() override { PYBIND11_OVERRIDE(int, VirtBase, get_code); }
+};
+
+struct WpOwner {
+    void set_wp(std::shared_ptr<VirtBase> sp) { wp = sp; }
+
+    int get_code() {
+        auto sp = wp.lock();
+        if (!sp) {
+            return -999;
+        }
+        return sp->get_code();
     }
 
-    WpBase() = default;
-    WpBase(const WpBase &) = delete;
-    virtual ~WpBase() = default;
-};
-
-struct PyWpBase : WpBase {
-    using WpBase::WpBase;
-    bool is_base_used() override { PYBIND11_OVERRIDE(bool, WpBase, is_base_used); }
-};
-
-struct WpBaseTester {
-    std::shared_ptr<WpBase> get_object() const { return m_obj.lock(); }
-    void set_object(std::shared_ptr<WpBase> obj) { m_obj = obj; }
-    bool is_expired() { return m_obj.expired(); }
-    bool is_base_used() { return m_obj.lock()->is_base_used(); }
-    std::weak_ptr<WpBase> m_obj;
+private:
+    std::weak_ptr<VirtBase> wp;
 };
 
 } // namespace class_sh_trampoline_weak_ptr
@@ -44,18 +40,12 @@ struct WpBaseTester {
 using namespace pybind11_tests::class_sh_trampoline_weak_ptr;
 
 TEST_SUBMODULE(class_sh_trampoline_weak_ptr, m) {
-    // For testing whether a python subclass of a C++ object can be accessed from a C++ weak_ptr
-
-    py::classh<WpBase, PyWpBase>(m, "WpBase")
+    py::classh<VirtBase, PyVirtBase>(m, "VirtBase")
         .def(py::init<>())
-        .def(py::init([](int) { return std::make_shared<PyWpBase>(); }))
-        .def("is_base_used", &WpBase::is_base_used)
-        .def("has_python_instance", &WpBase::has_python_instance);
+        .def("get_code", &VirtBase::get_code);
 
-    py::classh<WpBaseTester>(m, "WpBaseTester")
+    py::classh<WpOwner>(m, "WpOwner")
         .def(py::init<>())
-        .def("get_object", &WpBaseTester::get_object)
-        .def("set_object", &WpBaseTester::set_object)
-        .def("is_expired", &WpBaseTester::is_expired)
-        .def("is_base_used", &WpBaseTester::is_base_used);
+        .def("set_wp", &WpOwner::set_wp)
+        .def("get_code", &WpOwner::get_code);
 }
diff --git a/tests/test_class_sh_trampoline_weak_ptr.py b/tests/test_class_sh_trampoline_weak_ptr.py
index 545c1ad2e..0f24f0158 100644
--- a/tests/test_class_sh_trampoline_weak_ptr.py
+++ b/tests/test_class_sh_trampoline_weak_ptr.py
@@ -6,31 +6,22 @@ import env  # noqa: F401
 import pybind11_tests.class_sh_trampoline_weak_ptr as m
 
 
-@pytest.mark.skipif("env.GRAALPY", reason="Cannot reliably trigger GC")
-def test_weak_ptr_base():
-    tester = m.WpBaseTester()
-
-    obj = m.WpBase()
-
-    tester.set_object(obj)
-
-    assert tester.is_expired() is False
-    assert tester.is_base_used() is True
-    assert tester.get_object().is_base_used() is True
+class PyDrvd(m.VirtBase):
+    def get_code(self):
+        return 200
 
 
 @pytest.mark.skipif("env.GRAALPY", reason="Cannot reliably trigger GC")
-def test_weak_ptr_child():
-    class PyChild(m.WpBase):
-        def is_base_used(self):
-            return False
+@pytest.mark.parametrize(("vtype", "expected_code"), [(m.VirtBase, 100), (PyDrvd, 200)])
+def test_weak_ptr_base(vtype, expected_code):
+    wpo = m.WpOwner()
+    assert wpo.get_code() == -999
 
-    tester = m.WpBaseTester()
+    obj = vtype()
+    assert obj.get_code() == expected_code
 
-    obj = PyChild()
+    wpo.set_wp(obj)
+    assert wpo.get_code() == expected_code
 
-    tester.set_object(obj)
-
-    assert tester.is_expired() is False
-    assert tester.is_base_used() is False
-    assert tester.get_object().is_base_used() is False
+    del obj
+    assert wpo.get_code() == -999