niceSOFT/python3-attrs: Python Classes Without Boilerplate

tests/test_functional.py
818 строк20 KB
Hynek Schlawack
Fix message passing in frozen errors
14 мар 2026, 16:14
14 мар 2026, 16:14ce89f5d
# SPDX-License-Identifier: MIT

"""
End-to-end tests.
"""

import copy
import inspect
import pickle

from copy import deepcopy

import pytest

from hypothesis import given
from hypothesis.strategies import booleans

import attr

from attr._compat import PY_3_13_PLUS
from attr._make import NOTHING, Attribute
from attr.exceptions import FrozenInstanceError


@attr.s
class C1:
    x = attr.ib(validator=attr.validators.instance_of(int))
    y = attr.ib()


@attr.s(slots=True)
class C1Slots:
    x = attr.ib(validator=attr.validators.instance_of(int))
    y = attr.ib()


foo = None


@attr.s()
class C2:
    x = attr.ib(default=foo)
    y = attr.ib(default=attr.Factory(list))


@attr.s(slots=True)
class C2Slots:
    x = attr.ib(default=foo)
    y = attr.ib(default=attr.Factory(list))


@attr.s
class Base:
    x = attr.ib()

    def meth(self):
        return self.x


@attr.s(slots=True)
class BaseSlots:
    x = attr.ib()

    def meth(self):
        return self.x


@attr.s
class Sub(Base):
    y = attr.ib()


@attr.s(slots=True)
class SubSlots(BaseSlots):
    y = attr.ib()


@attr.s(frozen=True, slots=True)
class Frozen:
    x = attr.ib()


@attr.s
class SubFrozen(Frozen):
    y = attr.ib()


@attr.s(frozen=True, slots=False)
class FrozenNoSlots:
    x = attr.ib()


class Meta(type):
    pass


@attr.s
class WithMeta(metaclass=Meta):
    pass


@attr.s(slots=True)
class WithMetaSlots(metaclass=Meta):
    pass


FromMakeClass = attr.make_class("FromMakeClass", ["x"])


class TestFunctional:
    """
    Functional tests.
    """

    @pytest.mark.parametrize("cls", [C2, C2Slots])
    def test_fields(self, cls):
        """
        `attr.fields` works.
        """
        assert (
            Attribute(
                name="x",
                alias="x",
                default=foo,
                validator=None,
                repr=True,
                cmp=None,
                eq=True,
                order=True,
                hash=None,
                init=True,
                inherited=False,
                alias_is_default=True,
            ),
            Attribute(
                name="y",
                alias="y",
                default=attr.Factory(list),
                validator=None,
                repr=True,
                cmp=None,
                eq=True,
                order=True,
                hash=None,
                init=True,
                inherited=False,
                alias_is_default=True,
            ),
        ) == attr.fields(cls)

    @pytest.mark.parametrize("cls", [C1, C1Slots])
    def test_asdict(self, cls):
        """
        `attr.asdict` works.
        """
        assert {"x": 1, "y": 2} == attr.asdict(cls(x=1, y=2))

    @pytest.mark.parametrize("cls", [C1, C1Slots])
    def test_validator(self, cls):
        """
        `instance_of` raises `TypeError` on type mismatch.
        """
        with pytest.raises(TypeError) as e:
            cls("1", 2)

        # Using C1 explicitly, since slotted classes don't support this.
        assert (
            "'x' must be <class 'int'> (got '1' that is a <class 'str'>).",
            attr.fields(C1).x,
            int,
            "1",
        ) == e.value.args

    @given(booleans())
    def test_renaming(self, slots):
        """
        Private members are renamed but only in `__init__`.
        """

        @attr.s(slots=slots)
        class C3:
            _x = attr.ib()

        assert "C3(_x=1)" == repr(C3(x=1))

    @given(booleans(), booleans())
    def test_programmatic(self, slots, frozen):
        """
        `attr.make_class` works.
        """
        PC = attr.make_class("PC", ["a", "b"], slots=slots, frozen=frozen)

        assert (
            Attribute(
                name="a",
                alias="a",
                default=NOTHING,
                validator=None,
                repr=True,
                cmp=None,
                eq=True,
                order=True,
                hash=None,
                init=True,
                inherited=False,
                alias_is_default=True,
            ),
            Attribute(
                name="b",
                alias="b",
                default=NOTHING,
                validator=None,
                repr=True,
                cmp=None,
                eq=True,
                order=True,
                hash=None,
                init=True,
                inherited=False,
                alias_is_default=True,
            ),
        ) == attr.fields(PC)

    @pytest.mark.parametrize("cls", [Sub, SubSlots])
    def test_subclassing_with_extra_attrs(self, cls):
        """
        Subclassing (where the subclass has extra attrs) does what you'd hope
        for.
        """
        obj = object()
        i = cls(x=obj, y=2)
        assert i.x is i.meth() is obj
        assert i.y == 2
        if cls is Sub:
            assert f"Sub(x={obj}, y=2)" == repr(i)
        else:
            assert f"SubSlots(x={obj}, y=2)" == repr(i)

    @pytest.mark.parametrize("base", [Base, BaseSlots])
    def test_subclass_without_extra_attrs(self, base):
        """
        Subclassing (where the subclass does not have extra attrs) still
        behaves the same as a subclass with extra attrs.
        """

        class Sub2(base):
            pass

        obj = object()
        i = Sub2(x=obj)
        assert i.x is i.meth() is obj
        assert f"Sub2(x={obj})" == repr(i)

    @pytest.mark.parametrize(
        "frozen_class",
        [
            Frozen,  # has slots=True
            attr.make_class("FrozenToo", ["x"], slots=False, frozen=True),
        ],
    )
    def test_frozen_instance(self, frozen_class):
        """
        Frozen instances can't be modified (easily).
        """
        frozen = frozen_class(1)

        with pytest.raises(
            FrozenInstanceError, match="can't set attribute"
        ) as e:
            frozen.x = 2

        assert e.value.msg == e.value.args[0] == "can't set attribute"
        assert 1 == frozen.x

        with pytest.raises(
            FrozenInstanceError, match="can't set attribute"
        ) as e:
            del frozen.x

        assert e.value.msg == e.value.args[0] == "can't set attribute"
        assert 1 == frozen.x

    @pytest.mark.parametrize(
        "cls",
        [
            C1,
            C1Slots,
            C2,
            C2Slots,
            Base,
            BaseSlots,
            Sub,
            SubSlots,
            Frozen,
            FrozenNoSlots,
            FromMakeClass,
        ],
    )
    @pytest.mark.parametrize("protocol", range(2, pickle.HIGHEST_PROTOCOL + 1))
    def test_pickle_attributes(self, cls, protocol):
        """
        Pickling/un-pickling of Attribute instances works.
        """
        for attribute in attr.fields(cls):
            assert attribute == pickle.loads(pickle.dumps(attribute, protocol))

    @pytest.mark.parametrize(
        "cls",
        [
            C1,
            C1Slots,
            C2,
            C2Slots,
            Base,
            BaseSlots,
            Sub,
            SubSlots,
            Frozen,
            FrozenNoSlots,
            FromMakeClass,
        ],
    )
    @pytest.mark.parametrize("protocol", range(2, pickle.HIGHEST_PROTOCOL + 1))
    def test_pickle_object(self, cls, protocol):
        """
        Pickle object serialization works on all kinds of attrs classes.
        """
        obj = cls(123, 456) if len(attr.fields(cls)) == 2 else cls(123)

        assert repr(obj) == repr(pickle.loads(pickle.dumps(obj, protocol)))

    def test_subclassing_frozen_gives_frozen(self):
        """
        The frozen-ness of classes is inherited.  Subclasses of frozen classes
        are also frozen and can be instantiated.
        """
        i = SubFrozen("foo", "bar")

        assert i.x == "foo"
        assert i.y == "bar"

        with pytest.raises(FrozenInstanceError):
            i.x = "baz"

    @pytest.mark.parametrize("cls", [WithMeta, WithMetaSlots])
    def test_metaclass_preserved(self, cls):
        """
        Metaclass data is preserved.
        """
        assert Meta is type(cls)

    def test_default_decorator(self):
        """
        Default decorator sets the default and the respective method gets
        called.
        """

        @attr.s
        class C:
            x = attr.ib(default=1)
            y = attr.ib()

            @y.default
            def compute(self):
                return self.x + 1

        assert C(1, 2) == C()

    @pytest.mark.parametrize("weakref_slot", [True, False])
    def test_attrib_overwrite(self, slots, frozen, weakref_slot):
        """
        Subclasses can overwrite attributes of their base class.
        """

        @attr.s(slots=slots, frozen=frozen, weakref_slot=weakref_slot)
        class SubOverwrite(Base):
            x = attr.ib(default=attr.Factory(list))

        assert SubOverwrite([]) == SubOverwrite()

    def test_dict_patch_class(self):
        """
        dict-classes are never replaced.
        """

        class C:
            x = attr.ib()

        C_new = attr.s(C)

        assert C_new is C

    def test_hash_by_id(self):
        """
        With dict classes, hashing by ID is active for hash=False.  This is
        incorrect behavior but we have to retain it for
        backwards-compatibility.
        """

        @attr.s(unsafe_hash=False)
        class HashByIDBackwardCompat:
            x = attr.ib()

        assert hash(HashByIDBackwardCompat(1)) != hash(
            HashByIDBackwardCompat(1)
        )

        @attr.s(unsafe_hash=False, eq=False)
        class HashByID:
            x = attr.ib()

        assert hash(HashByID(1)) != hash(HashByID(1))

        @attr.s(unsafe_hash=True)
        class HashByValues:
            x = attr.ib()

        assert hash(HashByValues(1)) == hash(HashByValues(1))

    def test_handles_different_defaults(self):
        """
        Unhashable defaults + subclassing values work.
        """

        @attr.s
        class Unhashable:
            pass

        @attr.s
        class C:
            x = attr.ib(default=Unhashable())

        @attr.s
        class D(C):
            pass

    def test_unsafe_hash_false_eq_false(self, slots):
        """
        unsafe_hash=False and eq=False make a class hashable by ID.
        """

        @attr.s(unsafe_hash=False, eq=False, slots=slots)
        class C:
            pass

        assert hash(C()) != hash(C())

    def test_hash_deprecated(self):
        """
        Using the hash argument is deprecated.
        """

    def test_eq_false(self, slots):
        """
        eq=False makes a class hashable by ID.
        """

        @attr.s(eq=False, slots=slots)
        class C:
            pass

        # Ensure both objects live long enough such that their ids/hashes
        # can't be recycled. Thanks to Ask Hjorth Larsen for pointing that
        # out.
        c1 = C()
        c2 = C()

        assert hash(c1) != hash(c2)

    def test_overwrite_base(self):
        """
        Base classes can overwrite each other and the attributes are added
        in the order they are defined.
        """

        @attr.s
        class C:
            c = attr.ib(default=100)
            x = attr.ib(default=1)
            b = attr.ib(default=23)

        @attr.s
        class D(C):
            a = attr.ib(default=42)
            x = attr.ib(default=2)
            d = attr.ib(default=3.14)

        @attr.s
        class E(D):
            y = attr.ib(default=3)
            z = attr.ib(default=4)

        assert "E(c=100, b=23, a=42, x=2, d=3.14, y=3, z=4)" == repr(E())

    @pytest.mark.parametrize("base_slots", [True, False])
    @pytest.mark.parametrize("sub_slots", [True, False])
    @pytest.mark.parametrize("base_frozen", [True, False])
    @pytest.mark.parametrize("sub_frozen", [True, False])
    @pytest.mark.parametrize("base_weakref_slot", [True, False])
    @pytest.mark.parametrize("sub_weakref_slot", [True, False])
    @pytest.mark.parametrize("base_converter", [True, False])
    @pytest.mark.parametrize("sub_converter", [True, False])
    def test_frozen_slots_combo(
        self,
        base_slots,
        sub_slots,
        base_frozen,
        sub_frozen,
        base_weakref_slot,
        sub_weakref_slot,
        base_converter,
        sub_converter,
    ):
        """
        A class with a single attribute, inheriting from another class
        with a single attribute.
        """

        @attr.s(
            frozen=base_frozen,
            slots=base_slots,
            weakref_slot=base_weakref_slot,
        )
        class Base:
            a = attr.ib(converter=int if base_converter else None)

        @attr.s(
            frozen=sub_frozen, slots=sub_slots, weakref_slot=sub_weakref_slot
        )
        class Sub(Base):
            b = attr.ib(converter=int if sub_converter else None)

        i = Sub("1", "2")

        assert i.a == (1 if base_converter else "1")
        assert i.b == (2 if sub_converter else "2")

        if base_frozen or sub_frozen:
            with pytest.raises(FrozenInstanceError):
                i.a = "2"

            with pytest.raises(FrozenInstanceError):
                i.b = "3"

    def test_tuple_class_aliasing(self):
        """
        itemgetter and property are legal attribute names.
        """

        @attr.s
        class C:
            property = attr.ib()
            itemgetter = attr.ib()
            x = attr.ib()

        assert "property" == attr.fields(C).property.name
        assert "itemgetter" == attr.fields(C).itemgetter.name
        assert "x" == attr.fields(C).x.name

    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)

    def test_auto_exc_one_attrib(self, slots, frozen):
        """
        Having one attribute works with auto_exc=True.

        Easy to get wrong with tuple literals.
        """

        @attr.s(auto_exc=True, slots=slots, frozen=frozen)
        class FooError(Exception):
            x = attr.ib()

        FooError(1)

    def test_eq_only(self, slots, frozen):
        """
        Classes with order=False cannot be ordered.
        """

        @attr.s(eq=True, order=False, slots=slots, frozen=frozen)
        class C:
            x = attr.ib()

        possible_errors = (
            "unorderable types: C() < C()",
            "'<' not supported between instances of 'C' and 'C'",
            "unorderable types: C < C",  # old PyPy 3
        )

        with pytest.raises(TypeError) as ei:
            C(5) < C(6)

        assert ei.value.args[0] in possible_errors

    @pytest.mark.parametrize("cmp", [True, False])
    def test_attrib_cmp_shortcut(self, slots, cmp):
        """
        Setting cmp on `attr.ib`s sets both eq and order.
        """

        @attr.s(slots=slots)
        class C:
            x = attr.ib(cmp=cmp)

        assert cmp is attr.fields(C).x.eq
        assert cmp is attr.fields(C).x.order

    def test_no_setattr_if_validate_without_validators(self, slots):
        """
        If a class has on_setattr=attr.setters.validate (former default in NG
        APIs) but sets no validators, don't use the (slower) setattr in
        __init__.

        Regression test for #816.
        """

        @attr.s(on_setattr=attr.setters.validate, slots=slots)
        class C:
            x = attr.ib()

        @attr.s(on_setattr=attr.setters.validate, slots=slots)
        class D(C):
            y = attr.ib()

        src = inspect.getsource(D.__init__)

        assert "setattr" not in src
        assert "self.x = x" in src
        assert "self.y = y" in src
        assert object.__setattr__ == D.__setattr__

    def test_no_setattr_if_convert_without_converters(self, slots):
        """
        If a class has on_setattr=attr.setters.convert but sets no validators,
        don't use the (slower) setattr in __init__.
        """

        @attr.s(on_setattr=attr.setters.convert, slots=slots)
        class C:
            x = attr.ib()

        @attr.s(on_setattr=attr.setters.convert, slots=slots)
        class D(C):
            y = attr.ib()

        src = inspect.getsource(D.__init__)

        assert "setattr" not in src
        assert "self.x = x" in src
        assert "self.y = y" in src
        assert object.__setattr__ == D.__setattr__

    def test_no_setattr_with_ng_defaults(self, slots):
        """
        If a class has the NG default on_setattr=[convert, validate] but sets
        no validators or converters, don't use the (slower) setattr in
        __init__.
        """

        @attr.define(slots=slots)
        class C:
            x = attr.ib()

        src = inspect.getsource(C.__init__)

        assert "setattr" not in src
        assert "self.x = x" in src
        assert object.__setattr__ == C.__setattr__

        @attr.define(slots=slots)
        class D(C):
            y = attr.ib()

        src = inspect.getsource(D.__init__)

        assert "setattr" not in src
        assert "self.x = x" in src
        assert "self.y = y" in src
        assert object.__setattr__ == D.__setattr__

    def test_on_setattr_detect_inherited_validators(self):
        """
        _make_init detects the presence of a validator even if the field is
        inherited.
        """

        @attr.s(on_setattr=attr.setters.validate)
        class C:
            x = attr.ib(validator=42)

        @attr.s(on_setattr=attr.setters.validate)
        class D(C):
            y = attr.ib()

        src = inspect.getsource(D.__init__)

        assert "_setattr = _cached_setattr_get(self)" in src
        assert "_setattr('x', x)" in src
        assert "_setattr('y', y)" in src
        assert object.__setattr__ != D.__setattr__

    def test_unsafe_hash(self, slots):
        """
        attr.s(unsafe_hash=True) makes a class hashable.
        """

        @attr.s(slots=slots, unsafe_hash=True)
        class Hashable:
            pass

        assert hash(Hashable())

    def test_init_subclass(self, slots):
        """
        __attrs_init_subclass__ is called on subclasses.
        """
        REGISTRY = []

        @attr.s(slots=slots)
        class Base:
            @classmethod
            def __attrs_init_subclass__(cls):
                REGISTRY.append(cls)

        @attr.s(slots=slots)
        class ToRegister(Base):
            pass

        assert [ToRegister] == REGISTRY


@pytest.mark.skipif(not PY_3_13_PLUS, reason="requires Python 3.13+")
class TestReplace:
    def test_replaces(self):
        """
        copy.replace() is added by default and works like `attrs.evolve`.
        """
        inst = C1(1, 2)

        assert C1(1, 42) == copy.replace(inst, y=42)
        assert C1(42, 2) == copy.replace(inst, x=42)

    def test_already_has_one(self):
        """
        If the object already has a __replace__, it's left alone.
        """
        sentinel = object()

        @attr.s
        class C:
            x = attr.ib()

            __replace__ = sentinel

        assert sentinel == C.__replace__

    def test_invalid_field_name(self):
        """
        Invalid field names raise a TypeError.

        This is consistent with dataclasses.
        """
        inst = C1(1, 2)

        with pytest.raises(TypeError):
            copy.replace(inst, z=42)