Adding str_from_handle() to tests/test_pytypes.

Expanding test coverage only, no behavior change.

tests/test_pytypes.cpp

@@ -80,6 +80,7 @@ TEST_SUBMODULE(pytypes, m) {
     m.def("str_from_bytes", []() { return py::str(py::bytes("boo", 3)); });
     m.def("str_from_object", [](const py::object& obj) { return py::str(obj); });
     m.def("repr_from_object", [](const py::object& obj) { return py::repr(obj); });
+    m.def("str_from_handle", [](py::handle h) { return py::str(h); });
 
     m.def("str_format", []() {
         auto s1 = "{} + {} = {}"_s.format(1, 2, 3);

tests/test_pytypes.py

@@ -109,6 +109,16 @@ def __repr__(self):
     assert s1 == "1 + 2 = 3"
     assert s1 == s2
 
+    assert m.str_from_handle(A()) == "this is a str"
+
+    malformed_utf8 = b"\x80"
+    assert m.str_from_object(malformed_utf8) is malformed_utf8  # Probably surprising.
+    if env.PY2:
+        with pytest.raises(TypeError):
+            m.str_from_handle(malformed_utf8)
+    else:
+        assert m.str_from_handle(malformed_utf8) == "b'\\x80'"
+
 
 def test_bytes(doc):
     assert m.bytes_from_string().decode() == "foo"