Add test_cases_for_stubgen

Material to inform python/mypy#16306

Author: rwgk

tests/CMakeLists.txt

@@ -117,6 +117,7 @@ set(PYBIND11_TEST_FILES
     test_builtin_casters
     test_call_policies
     test_callbacks
+    test_cases_for_stubgen
     test_chrono
     test_class
     test_const_name

tests/test_cases_for_stubgen.cpp

@@ -0,0 +1,72 @@
+#include "pybind11/stl_bind.h"
+#include "pybind11_tests.h"
+
+#include <map>
+
+namespace test_cases_for_stubgen {
+
+struct user_type {
+    bool operator<(const user_type &) const { return false; }
+};
+
+struct minimal_caster {
+    static constexpr auto name = py::detail::const_name<user_type>();
+
+    static py::handle
+    cast(user_type const & /*src*/, py::return_value_policy /*policy*/, py::handle /*parent*/) {
+        return py::none().release();
+    }
+
+    // Maximizing simplicity. This will go terribly wrong for other arg types.
+    template <typename>
+    using cast_op_type = const user_type &;
+
+    // NOLINTNEXTLINE(google-explicit-constructor)
+    operator user_type const &() {
+        static user_type obj;
+        return obj;
+    }
+
+    bool load(py::handle /*src*/, bool /*convert*/) { return false; }
+};
+
+} // namespace test_cases_for_stubgen
+
+namespace pybind11 {
+namespace detail {
+
+template <>
+struct type_caster<test_cases_for_stubgen::user_type> : test_cases_for_stubgen::minimal_caster {};
+
+} // namespace detail
+} // namespace pybind11
+
+TEST_SUBMODULE(cases_for_stubgen, m) {
+    using namespace test_cases_for_stubgen;
+
+    m.def("pass_user_type", [](const user_type &) {});
+    m.def("return_user_type", []() { return user_type(); });
+
+    py::bind_map<std::map<int, user_type>>(m, "MapIntUserType");
+    py::bind_map<std::map<user_type, int>>(m, "MapUserTypeInt");
+
+#define MAP_TYPE(MapTypePythonName, ...)                                                          \
+    py::class_<__VA_ARGS__>(m, MapTypePythonName)                                                 \
+        .def(                                                                                     \
+            "keys",                                                                               \
+            [](const __VA_ARGS__ &v) { return py::make_key_iterator(v); },                        \
+            py::keep_alive<0, 1>())                                                               \
+        .def(                                                                                     \
+            "values",                                                                             \
+            [](const __VA_ARGS__ &v) { return py::make_value_iterator(v); },                      \
+            py::keep_alive<0, 1>())                                                               \
+        .def(                                                                                     \
+            "__iter__",                                                                           \
+            [](const __VA_ARGS__ &v) { return py::make_iterator(v.begin(), v.end()); },           \
+            py::keep_alive<0, 1>())
+
+    MAP_TYPE("MapFloatUserType", std::map<float, user_type>);
+    MAP_TYPE("MapUserTypeFloat", std::map<user_type, float>);
+
+#undef MAP_TYPE
+}

tests/test_cases_for_stubgen.py

@@ -0,0 +1,68 @@
+import pytest
+
+from pybind11_tests import cases_for_stubgen as m
+
+
+@pytest.mark.parametrize(
+    ("docstring", "expected"),
+    [
+        (
+            m.pass_user_type.__doc__,
+            'pass_user_type(arg0: Annotated[Any, "test_cases_for_stubgen::user_type"]) -> None\n',
+        ),
+        (
+            m.return_user_type.__doc__,
+            'return_user_type() -> Annotated[Any, "test_cases_for_stubgen::user_type"]\n',
+        ),
+        (
+            m.MapIntUserType.keys.__doc__,
+            "keys(self: pybind11_tests.cases_for_stubgen.MapIntUserType) -> pybind11_tests.cases_for_stubgen.KeysView[int]\n",
+        ),
+        (
+            m.MapIntUserType.values.__doc__,
+            "values(self: pybind11_tests.cases_for_stubgen.MapIntUserType) -> pybind11_tests.cases_for_stubgen.ValuesView[test_cases_for_stubgen::user_type]\n",
+        ),
+        (
+            m.MapIntUserType.items.__doc__,
+            "items(self: pybind11_tests.cases_for_stubgen.MapIntUserType) -> pybind11_tests.cases_for_stubgen.ItemsView[int, test_cases_for_stubgen::user_type]\n",
+        ),
+        (
+            m.MapUserTypeInt.keys.__doc__,
+            "keys(self: pybind11_tests.cases_for_stubgen.MapUserTypeInt) -> pybind11_tests.cases_for_stubgen.KeysView[test_cases_for_stubgen::user_type]\n",
+        ),
+        (
+            m.MapUserTypeInt.values.__doc__,
+            "values(self: pybind11_tests.cases_for_stubgen.MapUserTypeInt) -> pybind11_tests.cases_for_stubgen.ValuesView[int]\n",
+        ),
+        (
+            m.MapUserTypeInt.items.__doc__,
+            "items(self: pybind11_tests.cases_for_stubgen.MapUserTypeInt) -> pybind11_tests.cases_for_stubgen.ItemsView[test_cases_for_stubgen::user_type, int]\n",
+        ),
+        (
+            m.MapFloatUserType.keys.__doc__,
+            "keys(self: pybind11_tests.cases_for_stubgen.MapFloatUserType) -> Iterator[float]\n",
+        ),
+        (
+            m.MapFloatUserType.values.__doc__,
+            'values(self: pybind11_tests.cases_for_stubgen.MapFloatUserType) -> Iterator[Annotated[Any, "test_cases_for_stubgen::user_type"]]\n',
+        ),
+        (
+            m.MapFloatUserType.__iter__.__doc__,
+            '__iter__(self: pybind11_tests.cases_for_stubgen.MapFloatUserType) -> Iterator[tuple[float, Annotated[Any, "test_cases_for_stubgen::user_type"]]]\n',
+        ),
+        (
+            m.MapUserTypeFloat.keys.__doc__,
+            'keys(self: pybind11_tests.cases_for_stubgen.MapUserTypeFloat) -> Iterator[Annotated[Any, "test_cases_for_stubgen::user_type"]]\n',
+        ),
+        (
+            m.MapUserTypeFloat.values.__doc__,
+            "values(self: pybind11_tests.cases_for_stubgen.MapUserTypeFloat) -> Iterator[float]\n",
+        ),
+        (
+            m.MapUserTypeFloat.__iter__.__doc__,
+            '__iter__(self: pybind11_tests.cases_for_stubgen.MapUserTypeFloat) -> Iterator[tuple[Annotated[Any, "test_cases_for_stubgen::user_type"], float]]\n',
+        ),
+    ],
+)
+def test_docstring(docstring, expected):
+    assert docstring == expected