Added initial testing module for stubgen tests.

Author: timohl

tests/CMakeLists.txt

@@ -169,6 +169,7 @@ set(PYBIND11_TEST_FILES
     test_smart_ptr
     test_stl
     test_stl_binders
+    test_stubgen
     test_tagbased_polymorphic
     test_thread
     test_type_caster_pyobject_ptr

tests/requirements.txt

@@ -9,6 +9,7 @@ numpy~=1.21.5; platform_python_implementation=="CPython" and python_version>="3.
 numpy~=1.22.2; platform_python_implementation=="CPython" and python_version=="3.10"
 numpy~=1.26.0; platform_python_implementation=="CPython" and python_version>="3.11" and python_version<"3.13"
 numpy~=2.2.0; platform_python_implementation=="CPython" and python_version=="3.13"
+pybind11-stubgen
 pytest>=6
 pytest-timeout
 scipy~=1.5.4; platform_python_implementation=="CPython" and python_version<"3.10"

tests/test_stubgen.cpp

@@ -0,0 +1,5 @@
+#include "pybind11_tests.h"
+
+TEST_SUBMODULE(stubgen, m) {
+    m.def("add_int", [](int a, int b) { return a + b; }, "a"_a, "b"_a);
+}

tests/test_stubgen.py

@@ -0,0 +1,7 @@
+from __future__ import annotations
+
+from pybind11_tests import stubgen as m
+
+
+def test_stubgen() -> None:
+    assert m.add_int(1, 2) == 3