Function test_struct_meta_inheritance

tests/unit/test_struct_meta.py:115–234

Test that StructMeta can be inherited in Python code.

()

def test_struct_meta_inheritance():
    """Test that StructMeta can be inherited in Python code."""

    class CustomMeta(StructMeta):
        """A custom metaclass that inherits from StructMeta.

        This metaclass adds a kw_only_default parameter that can be used to
        set the default kw_only value for all subclasses.

        When a class is created with this metaclass:
        1. If kw_only is explicitly specified, use that value
        2. If kw_only is not specified but kw_only_default is, use kw_only_default
        3. If neither is specified but a parent class has kw_only_default defined,
           use the parent's kw_only_default
        4. Otherwise, default to False
        """

        # Class attribute to store kw_only_default settings for each class
        _kw_only_default_settings = {}

        def __new__(mcls, name, bases, namespace, **kwargs):
            # Check if kw_only is explicitly specified
            kw_only_specified = "kw_only" in kwargs

            # Process kw_only_default parameter
            kw_only_default = kwargs.pop("kw_only_default", None)

            # If kw_only_default is specified, store it
            if kw_only_default is not None:
                # Remember this setting for future subclasses
                mcls._kw_only_default_settings[name] = kw_only_default
            else:
                # Check if any parent class has kw_only_default defined
                for base in bases:
                    base_name = base.__name__
                    if base_name in mcls._kw_only_default_settings:
                        # Use parent's kw_only_default
                        kw_only_default = mcls._kw_only_default_settings[base_name]
                        break

            # If kw_only is not specified but kw_only_default is available, use it
            if not kw_only_specified and kw_only_default is not None:
                kwargs["kw_only"] = kw_only_default

            # Create the class
            return super().__new__(mcls, name, bases, namespace, **kwargs)

    # Test basic functionality - without kw_only_default
    class SimpleModel(metaclass=CustomMeta):
        x: int
        y: str

    # Verify the class was created correctly
    assert isinstance(SimpleModel, CustomMeta)
    assert issubclass(CustomMeta, StructMeta)

    # Test creating an instance with positional arguments (should work)
    instance = SimpleModel(1, "test")