pybind11 equivalent of Boost.Python test similar to reproducer under #1333

tests/test_cpp_base_py_derived.cpp

+// pybind11 equivalent of Boost.Python test:
+// https://github.com/rwgk/rwgk_tbx/blob/6c9a6d6bc72d5c1b8609724433259c5b47178680/cpp_base_py_derived_ext.cpp
+// See also: https://github.com/pybind/pybind11/issues/1333 (this was the starting point)
+
+#include "pybind11_tests.h"
+
+namespace pybind11_tests {
+namespace cpp_base_py_derived {
+
+struct base {
+  base() : base_num(100) {}
+
+  virtual int get_num() const { return base_num; }
+
+  virtual std::shared_ptr<base> clone() const {
+    return std::shared_ptr<base>(new base(150));
+  }
+
+  virtual ~base() = default;
+
+ private:
+  explicit base(int num) : base_num(num) {}
+  int base_num;
+};
+
+inline int get_num(std::shared_ptr<base> b) { return b->get_num(); }
+
+inline int clone_get_num(std::shared_ptr<base> b) {
+  std::shared_ptr<base> c = b->clone();
+  return (b->get_num() + 3) * 1000 + (c->get_num() + 7);
+}
+
+struct base_trampoline : public base {
+  using base::base;
+
+  int get_num() const override {
+    PYBIND11_OVERRIDE(int, base, get_num);
+  }
+
+  std::shared_ptr<base> clone() const override {
+    PYBIND11_OVERRIDE(std::shared_ptr<base>, base, clone);
+  }
+};
+
+TEST_SUBMODULE(cpp_base_py_derived, m) {
+  py::class_<base, base_trampoline, std::shared_ptr<base>>(m, "base")
+    .def(py::init<>())
+    .def("get_num", &base::get_num)
+    .def("clone", &base::clone)
+  ;
+
+  m.def("get_num", get_num);
+  m.def("clone_get_num", clone_get_num);
+}
+
+}  // namespace cpp_base_py_derived
+}  // namespace pybind11_tests

tests/test_cpp_base_py_derived.py

+# -*- coding: utf-8 -*-
+# pybind11 equivalent of Boost.Python test:
+# https://github.com/rwgk/rwgk_tbx/blob/6c9a6d6bc72d5c1b8609724433259c5b47178680/tst_cpp_base_py_derived.py
+# See also: https://github.com/pybind/pybind11/issues/1333 (this was the starting point)
+import pytest
+
+from pybind11_tests import cpp_base_py_derived as m
+
+
+class drvd(m.base):
+
+  def __init__(self, _num = 200):
+    super().__init__()
+    self._drvd_num = _num
+
+  def get_num(self):
+    return self._drvd_num
+
+  def clone(self):
+    return drvd(250)
+
+
+def test_base():
+  b = m.base()
+  assert b.get_num() == 100
+  m.get_num(b) == 100
+  bc = b.clone()
+  assert bc.get_num() == 150
+  assert m.clone_get_num(b) == 103157
+
+
+def test_drvd():
+  d = drvd()
+  assert d.get_num() == 200
+  assert m.get_num(d) == 200
+  dc = d.clone()
+  assert dc.get_num() == 250
+  assert m.clone_get_num(d) == 203257