def test_setdefault_without_default_with_non_existent(self):
properties = PropertyDict({"name": "Alice"})
value = properties.setdefault("age")
assert properties == {"name": "Alice"}
assert value is None
def test_setdefault_with_default_with_non_existent(self):
properties = PropertyDict({"name": "Alice"})
value = properties.setdefault("age", 33)
assert properties == {"name": "Alice", "age": 33}
assert value == 33
def test_setdefault_without_default_with_existing(self):
properties = PropertyDict({"name": "Alice", "age": 33})
value = properties.setdefault("age")
assert properties == {"name": "Alice", "age": 33}
assert value == 33
