Python attr.make_class() Examples

def test_convert_before_validate(self):
        """
        Validation happens after conversion.
        """

        def validator(inst, attr, val):
            raise RuntimeError("foo")

        C = make_class(
            "C",
            {
                "x": attr.ib(validator=validator, converter=lambda v: 1 / 0),
                "y": attr.ib(),
            },
        )
        with pytest.raises(ZeroDivisionError):
            C(1, 2) 

def test_bases(self):
        """
        Parameter bases default to (object,) and subclasses correctly
        """

        class D(object):
            pass

        cls = make_class("C", {})

        assert cls.__mro__[-1] == object

        cls = make_class("C", {}, bases=(D,))

        assert D in cls.__mro__
        assert isinstance(cls(), D) 

def test_metadata_present(self, list_of_attrs):
        """
        Assert dictionaries are copied and present.
        """
        C = make_class("C", dict(zip(gen_attr_names(), list_of_attrs)))

        for hyp_attr, class_attr in zip(list_of_attrs, fields(C)):
            if hyp_attr.metadata is None:
                # The default is a singleton empty dict.
                assert class_attr.metadata is not None
                assert len(class_attr.metadata) == 0
            else:
                assert hyp_attr.metadata == class_attr.metadata

                # Once more, just to assert getting items and iteration.
                for k in class_attr.metadata:
                    assert hyp_attr.metadata[k] == class_attr.metadata[k]
                    assert hyp_attr.metadata.get(k) == class_attr.metadata.get(
                        k
                    ) 

def test_convert_property(self, val, init):
        """
        Property tests for attributes using converter.
        """
        C = make_class(
            "C",
            {
                "y": attr.ib(),
                "x": attr.ib(
                    init=init, default=val, converter=lambda v: v + 1
                ),
            },
        )
        c = C(2)

        assert c.x == val + 1
        assert c.y == 2 

def test_converter_factory_property(self, val, init):
        """
        Property tests for attributes with converter, and a factory default.
        """
        C = make_class(
            "C",
            ordered_dict(
                [
                    ("y", attr.ib()),
                    (
                        "x",
                        attr.ib(
                            init=init,
                            default=Factory(lambda: val),
                            converter=lambda v: v + 1,
                        ),
                    ),
                ]
            ),
        )
        c = C(2)

        assert c.x == val + 1
        assert c.y == 2 

def test_run_validators(self):
        """
        Setting `_run_validators` to False prevents validators from running.
        """
        _config._run_validators = False
        obj = object()

        def raiser(_, __, ___):
            raise Exception(obj)

        C = make_class("C", {"x": attr.ib(validator=raiser)})
        c = C(1)
        validate(c)
        assert 1 == c.x
        _config._run_validators = True

        with pytest.raises(Exception):
            validate(c)

        with pytest.raises(Exception) as e:
            C(1)
        assert (obj,) == e.value.args 

def test_frozen(self):
        """
        Converters circumvent immutability.
        """
        C = make_class(
            "C", {"x": attr.ib(converter=lambda v: int(v))}, frozen=True
        )
        C("1") 

def _make_process_subclass(self):
        p_cls = attr.make_class(
            self._base_cls.__name__,
            self._reset_attributes(),
            bases=(self._base_cls,),
            init=False,
            repr=False,
        )

        setattr(p_cls, "__init__", _process_cls_init)
        setattr(p_cls, "__repr__", repr_process)
        setattr(p_cls, "__xsimlab_process__", True)
        setattr(p_cls, "__xsimlab_executor__", _ProcessExecutor(p_cls))

        return p_cls 

def test_simple_roundtrip_defaults(cls_and_vals, strat):
    """
    Simple classes with metadata can be unstructured and restructured.
    """
    a, _ = cls_and_vals
    cl = make_class("HypClass", {"a": a})
    converter = Converter(unstruct_strat=strat)
    inst = cl()
    assert converter.unstructure(
        converter.structure({}, cl)
    ) == converter.unstructure(inst)
    assert inst == converter.structure(converter.unstructure(inst), cl) 

def test_exception(self):
        with pytest.raises(ValueError) as excinfo:
            TestParams5a = attr.make_class('TestParams5a', {'f1': field(0), 'f2': field()})
        assert excinfo.type == ValueError

        with pytest.raises(ValueError) as excinfo:
            @attr.s()
            class TestParams5b(Registry):
                f1 = field(0)  # type: int
                # this is not allowed
                f2 = field()  # type: int

        assert excinfo.type == ValueError 

def test_repr_str(self):
        """
        Trying to add a `__str__` without having a `__repr__` raises a
        ValueError.
        """
        with pytest.raises(ValueError) as ei:
            make_class("C", {}, repr=False, str=True)

        assert (
            "__str__ can only be generated if a __repr__ exists.",
        ) == ei.value.args 

def test_not_none_metadata(self, list_of_attrs):
        """
        Non-empty metadata attributes exist as fields after ``@attr.s``.
        """
        C = make_class("C", dict(zip(gen_attr_names(), list_of_attrs)))

        assert len(fields(C)) > 0

        for cls_a, raw_a in zip(fields(C), list_of_attrs):
            assert cls_a.metadata != {}
            assert cls_a.metadata == raw_a.metadata 

def test_empty_metadata_singleton(self, list_of_attrs):
        """
        All empty metadata attributes share the same empty metadata dict.
        """
        C = make_class("C", dict(zip(gen_attr_names(), list_of_attrs)))
        for a in fields(C)[1:]:
            assert a.metadata is fields(C)[0].metadata 

def test_multiple_empty(self):
        """
        Empty list/tuple for validator is the same as None.
        """
        C1 = make_class("C", {"x": attr.ib(validator=[])})
        C2 = make_class("C", {"x": attr.ib(validator=None)})

        assert inspect.getsource(C1.__init__) == inspect.getsource(C2.__init__)


# Hypothesis seems to cache values, so the lists of attributes come out
# unsorted. 

def test_propagates(self):
        """
        The exception of the validator is handed through.
        """

        def raiser(_, __, value):
            if value == 42:
                raise FloatingPointError

        C = make_class("C", {"x": attr.ib(validator=raiser)})
        i = C(1)
        i.x = 42

        with pytest.raises(FloatingPointError):
            validate(i) 

def test_success(self):
        """
        If the validator succeeds, nothing gets raised.
        """
        C = make_class(
            "C", {"x": attr.ib(validator=lambda *a: None), "y": attr.ib()}
        )
        validate(C(1, 2)) 

def __attrs_post_init__(self):
        """ Build the constructor that can create feature structures of this type """
        name = _string_to_valid_classname(self.name)
        fields = {feature.name: attr.ib(default=None, repr=(feature.name != "sofa")) for feature in self.all_features}
        fields["type"] = attr.ib(default=self.name)

        self._constructor = attr.make_class(name, fields, bases=(FeatureStructure,), slots=True, eq=False, order=False) 

def test_convert(self):
        """
        Return value of converter is used as the attribute's value.
        """
        C = make_class(
            "C", {"x": attr.ib(converter=lambda v: v + 1), "y": attr.ib()}
        )
        c = C(1, 2)

        assert c.x == 2
        assert c.y == 2 

def test_make_class_ordered(self):
        """
        If `make_class()` is passed ordered attrs, their order is respected
        instead of the counter.
        """
        b = attr.ib(default=2)
        a = attr.ib(default=1)

        C = attr.make_class("C", ordered_dict([("a", a), ("b", b)]))

        assert "C(a=1, b=2)" == repr(C()) 

def test_missing_sys_getframe(self, monkeypatch):
        """
        `make_class()` does not fail when `sys._getframe()` is not available.
        """
        monkeypatch.delattr(sys, "_getframe")
        C = make_class("C", ["x"])

        assert 1 == len(C.__attrs_attrs__) 

def test_catches_wrong_attrs_type(self):
        """
        Raise `TypeError` if an invalid type for attrs is passed.
        """
        with pytest.raises(TypeError) as e:
            make_class("C", object())

        assert ("attrs argument must be a dict or a list.",) == e.value.args 

def test_attr_args(self):
        """
        attributes_arguments are passed to attributes
        """
        C = make_class("C", ["x"], repr=False)

        assert repr(C(1)).startswith("<tests.test_make.C object at 0x") 

def test_dict(self):
        """
        Passing a dict of name: _CountingAttr creates an equivalent class.
        """
        C1 = make_class(
            "C1", {"a": attr.ib(default=42), "b": attr.ib(default=None)}
        )

        @attr.s
        class C2(object):
            a = attr.ib(default=42)
            b = attr.ib(default=None)

        assert C1.__attrs_attrs__ == C2.__attrs_attrs__ 

def test_simple(self, ls):
        """
        Passing a list of strings creates attributes with default args.
        """
        C1 = make_class("C1", ls(["a", "b"]))

        @attr.s
        class C2(object):
            a = attr.ib()
            b = attr.ib()

        assert C1.__attrs_attrs__ == C2.__attrs_attrs__ 

def test_auto_exc(self, slots, frozen):
        """
        Classes with auto_exc=True have a Exception-style __str__, compare and
        hash by id, and store the fields additionally in self.args.
        """

        @attr.s(auto_exc=True, slots=slots, frozen=frozen)
        class FooError(Exception):
            x = attr.ib()
            y = attr.ib(init=False, default=42)
            z = attr.ib(init=False)
            a = attr.ib()

        FooErrorMade = attr.make_class(
            "FooErrorMade",
            bases=(Exception,),
            attrs={
                "x": attr.ib(),
                "y": attr.ib(init=False, default=42),
                "z": attr.ib(init=False),
                "a": attr.ib(),
            },
            auto_exc=True,
            slots=slots,
            frozen=frozen,
        )

        assert FooError(1, "foo") != FooError(1, "foo")
        assert FooErrorMade(1, "foo") != FooErrorMade(1, "foo")

        for cls in (FooError, FooErrorMade):
            with pytest.raises(cls) as ei1:
                raise cls(1, "foo")

            with pytest.raises(cls) as ei2:
                raise cls(1, "foo")

            e1 = ei1.value
            e2 = ei2.value

            assert e1 is e1
            assert e1 == e1
            assert e2 == e2
            assert e1 != e2
            assert "(1, 'foo')" == str(e1) == str(e2)
            assert (1, "foo") == e1.args == e2.args

            hash(e1) == hash(e1)
            hash(e2) == hash(e2)

            if not frozen:
                deepcopy(e1)
                deepcopy(e2)