From a3fd84dd8e5cc22f30a9f7a017613660cedae157 Mon Sep 17 00:00:00 2001
From: "Ralf W. Grosse-Kunstleve" <rwgk@google.com>
Date: Fri, 1 Dec 2023 10:32:16 -0800
Subject: [PATCH] Add `test_pyobject_ptr_from_handle_nullptr` (no production
 code changes), to firmly establish that this part works already.

---
 tests/test_type_caster_pyobject_ptr.cpp | 12 ++++++++++++
 tests/test_type_caster_pyobject_ptr.py  |  4 ++++
 2 files changed, 16 insertions(+)

diff --git a/tests/test_type_caster_pyobject_ptr.cpp b/tests/test_type_caster_pyobject_ptr.cpp
index 8069f7dcd9..30029c88d1 100644
--- a/tests/test_type_caster_pyobject_ptr.cpp
+++ b/tests/test_type_caster_pyobject_ptr.cpp
@@ -127,4 +127,16 @@ TEST_SUBMODULE(type_caster_pyobject_ptr, m) {
         (void) py::cast(*ptr);
     }
 #endif
+
+    m.def("pyobject_ptr_from_handle_nullptr", []() {
+        py::handle handle_nullptr;
+        if (handle_nullptr.ptr() != nullptr) {
+            return "UNEXPECTED: handle_nullptr.ptr() != nullptr";
+        }
+        auto *pyobject_ptr_from_handle = py::cast<PyObject *>(handle_nullptr);
+        if (pyobject_ptr_from_handle != nullptr) {
+            return "UNEXPECTED: pyobject_ptr_from_handle != nullptr";
+        }
+        return "SUCCESS";
+    });
 }
diff --git a/tests/test_type_caster_pyobject_ptr.py b/tests/test_type_caster_pyobject_ptr.py
index 1f1ece2baf..c598f9e573 100644
--- a/tests/test_type_caster_pyobject_ptr.py
+++ b/tests/test_type_caster_pyobject_ptr.py
@@ -102,3 +102,7 @@ def test_return_list_pyobject_ptr_reference():
 def test_type_caster_name_via_incompatible_function_arguments_type_error():
     with pytest.raises(TypeError, match=r"1\. \(arg0: object, arg1: int\) -> None"):
         m.pass_pyobject_ptr_and_int(ValueHolder(101), ValueHolder(202))
+
+
+def test_pyobject_ptr_from_handle_nullptr():
+    assert m.pyobject_ptr_from_handle_nullptr() == "SUCCESS"