modify to show default args

Author: EricCousineau-TRI

tests/test_pytypes.cpp

@@ -319,11 +319,13 @@ TEST_SUBMODULE(pytypes, m) {
         return a[py::slice(0, -1, 2)];
     });
 
-    m.def("test_str_with_cpp_default_none", []() {
-        auto my_func = [](py::str value = py::none()) {
-            return value;
-        };
-        return py::make_tuple(my_func(), my_func("Hello"));
+    // See #2361
+    m.def("test_str_with_default_arg_none" ,[](py::str value) {
+        return value;
+    }, py::arg("value") = py::none());
+    m.def("test_str_assign_none", []() {
+        py::str is_this_none = py::none();
+        return is_this_none;
     });
 
     m.def("test_memoryview_object", [](py::buffer b) {

tests/test_pytypes.py

@@ -281,8 +281,9 @@ def test_list_slicing():
     assert li[::2] == m.test_list_slicing(li)
 
 
-def test_str_with_cpp_default_none():
-    assert m.test_str_with_cpp_default_none() == (None, "Hello")
+def test_str_with_none():
+    assert m.test_str_assign_none() is None
+    assert m.test_str_with_default_arg_none() is None
 
 
 @pytest.mark.parametrize('method, args, fmt, expected_view', [