454 lines
12 KiB
Python
454 lines
12 KiB
Python
# SPDX-License-Identifier: MIT
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import pickle
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import pytest
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import attr
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from attr import setters
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from attr.exceptions import FrozenAttributeError
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from attr.validators import instance_of, matches_re
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@attr.s(frozen=True)
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class Frozen:
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x = attr.ib()
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@attr.s
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class WithOnSetAttrHook:
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x = attr.ib(on_setattr=lambda *args: None)
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class TestSetAttr:
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def test_change(self):
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"""
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The return value of a hook overwrites the value. But they are not run
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on __init__.
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"""
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def hook(*a, **kw):
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return "hooked!"
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@attr.s
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class Hooked:
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x = attr.ib(on_setattr=hook)
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y = attr.ib()
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h = Hooked("x", "y")
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assert "x" == h.x
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assert "y" == h.y
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h.x = "xxx"
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h.y = "yyy"
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assert "yyy" == h.y
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assert "hooked!" == h.x
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def test_frozen_attribute(self):
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"""
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Frozen attributes raise FrozenAttributeError, others are not affected.
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"""
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@attr.s
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class PartiallyFrozen:
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x = attr.ib(on_setattr=setters.frozen)
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y = attr.ib()
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pf = PartiallyFrozen("x", "y")
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pf.y = "yyy"
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assert "yyy" == pf.y
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with pytest.raises(FrozenAttributeError):
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pf.x = "xxx"
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assert "x" == pf.x
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@pytest.mark.parametrize(
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"on_setattr",
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[setters.validate, [setters.validate], setters.pipe(setters.validate)],
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)
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def test_validator(self, on_setattr):
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"""
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Validators are run and they don't alter the value.
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"""
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@attr.s(on_setattr=on_setattr)
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class ValidatedAttribute:
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x = attr.ib()
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y = attr.ib(validator=[instance_of(str), matches_re("foo.*qux")])
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va = ValidatedAttribute(42, "foobarqux")
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with pytest.raises(TypeError) as ei:
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va.y = 42
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assert "foobarqux" == va.y
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assert ei.value.args[0].startswith("'y' must be <")
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with pytest.raises(ValueError) as ei:
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va.y = "quxbarfoo"
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assert ei.value.args[0].startswith("'y' must match regex '")
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assert "foobarqux" == va.y
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va.y = "foobazqux"
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assert "foobazqux" == va.y
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def test_pipe(self):
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"""
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Multiple hooks are possible, in that case the last return value is
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used. They can be supplied using the pipe functions or by passing a
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list to on_setattr.
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"""
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taken = None
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def takes_all(val, instance, attrib):
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nonlocal taken
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taken = val, instance, attrib
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return val
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s = [setters.convert, lambda _, __, nv: nv + 1]
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@attr.s
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class Piped:
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x1 = attr.ib(
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converter=[
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attr.Converter(
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takes_all, takes_field=True, takes_self=True
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),
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int,
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],
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on_setattr=setters.pipe(*s),
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)
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x2 = attr.ib(converter=int, on_setattr=s)
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p = Piped("41", "22")
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assert ("41", p) == taken[:-1]
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assert "x1" == taken[-1].name
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assert 41 == p.x1
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assert 22 == p.x2
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p.x1 = "41"
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p.x2 = "22"
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assert 42 == p.x1
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assert 23 == p.x2
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def test_make_class(self):
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"""
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on_setattr of make_class gets forwarded.
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"""
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C = attr.make_class("C", {"x": attr.ib()}, on_setattr=setters.frozen)
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c = C(1)
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with pytest.raises(FrozenAttributeError):
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c.x = 2
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def test_no_validator_no_converter(self):
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"""
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validate and convert tolerate missing validators and converters.
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"""
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@attr.s(on_setattr=[setters.convert, setters.validate])
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class C:
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x = attr.ib()
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c = C(1)
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c.x = 2
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assert 2 == c.x
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def test_validate_respects_run_validators_config(self):
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"""
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If run validators is off, validate doesn't run them.
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"""
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@attr.s(on_setattr=setters.validate)
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class C:
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x = attr.ib(validator=attr.validators.instance_of(int))
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c = C(1)
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attr.set_run_validators(False)
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c.x = "1"
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assert "1" == c.x
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attr.set_run_validators(True)
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with pytest.raises(TypeError) as ei:
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c.x = "1"
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assert ei.value.args[0].startswith("'x' must be <")
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def test_frozen_on_setattr_class_is_caught(self):
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"""
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@attr.s(on_setattr=X, frozen=True) raises an ValueError.
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"""
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with pytest.raises(ValueError) as ei:
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@attr.s(frozen=True, on_setattr=setters.validate)
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class C:
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x = attr.ib()
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assert "Frozen classes can't use on_setattr." == ei.value.args[0]
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def test_frozen_on_setattr_attribute_is_caught(self):
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"""
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attr.ib(on_setattr=X) on a frozen class raises an ValueError.
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"""
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with pytest.raises(ValueError) as ei:
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@attr.s(frozen=True)
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class C:
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x = attr.ib(on_setattr=setters.validate)
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assert "Frozen classes can't use on_setattr." == ei.value.args[0]
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def test_setattr_reset_if_no_custom_setattr(self, slots):
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"""
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If a class with an active setattr is subclassed and no new setattr
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is generated, the __setattr__ is set to object.__setattr__.
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We do the double test because of Python 2.
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"""
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def boom(*args):
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pytest.fail("Must not be called.")
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@attr.s
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class Hooked:
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x = attr.ib(on_setattr=boom)
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@attr.s(slots=slots)
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class NoHook(WithOnSetAttrHook):
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x = attr.ib()
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assert NoHook.__setattr__ == object.__setattr__
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assert 1 == NoHook(1).x
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assert Hooked.__attrs_own_setattr__
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assert not NoHook.__attrs_own_setattr__
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assert WithOnSetAttrHook.__attrs_own_setattr__
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def test_setattr_inherited_do_not_reset(self, slots):
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"""
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If we inherit a __setattr__ that has been written by the user, we must
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not reset it unless necessary.
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"""
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class A:
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"""
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Not an attrs class on purpose to prevent accidental resets that
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would render the asserts meaningless.
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"""
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def __setattr__(self, *args):
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pass
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@attr.s(slots=slots)
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class B(A):
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pass
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assert B.__setattr__ == A.__setattr__
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@attr.s(slots=slots)
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class C(B):
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pass
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assert C.__setattr__ == A.__setattr__
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def test_pickling_retains_attrs_own(self, slots):
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"""
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Pickling/Unpickling does not lose ownership information about
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__setattr__.
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"""
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i = WithOnSetAttrHook(1)
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assert True is i.__attrs_own_setattr__
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i2 = pickle.loads(pickle.dumps(i))
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assert True is i2.__attrs_own_setattr__
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WOSAH = pickle.loads(pickle.dumps(WithOnSetAttrHook))
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assert True is WOSAH.__attrs_own_setattr__
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def test_slotted_class_can_have_custom_setattr(self):
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"""
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A slotted class can define a custom setattr and it doesn't get
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overwritten.
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Regression test for #680.
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"""
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@attr.s(slots=True)
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class A:
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def __setattr__(self, key, value):
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raise SystemError
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with pytest.raises(SystemError):
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A().x = 1
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@pytest.mark.xfail(raises=attr.exceptions.FrozenAttributeError)
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def test_slotted_confused(self):
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"""
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If we have a in-between non-attrs class, setattr reset detection
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should still work, but currently doesn't.
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It works with dict classes because we can look the finished class and
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patch it. With slotted classes we have to deduce it ourselves.
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"""
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@attr.s(slots=True)
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class A:
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x = attr.ib(on_setattr=setters.frozen)
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class B(A):
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pass
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@attr.s(slots=True)
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class C(B):
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x = attr.ib()
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C(1).x = 2
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def test_setattr_auto_detect_if_no_custom_setattr(self, slots):
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"""
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It's possible to remove the on_setattr hook from an attribute and
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therefore write a custom __setattr__.
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"""
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assert 1 == WithOnSetAttrHook(1).x
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@attr.s(auto_detect=True, slots=slots)
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class RemoveNeedForOurSetAttr(WithOnSetAttrHook):
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x = attr.ib()
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def __setattr__(self, name, val):
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object.__setattr__(self, name, val * 2)
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i = RemoveNeedForOurSetAttr(1)
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assert not RemoveNeedForOurSetAttr.__attrs_own_setattr__
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assert 2 == i.x
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def test_setattr_restore_respects_auto_detect(self, slots):
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"""
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If __setattr__ should be restored but the user supplied its own and
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set auto_detect, leave is alone.
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"""
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@attr.s(auto_detect=True, slots=slots)
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class CustomSetAttr:
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def __setattr__(self, _, __):
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pass
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assert CustomSetAttr.__setattr__ != object.__setattr__
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def test_setattr_auto_detect_frozen(self, slots):
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"""
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frozen=True together with a detected custom __setattr__ are rejected.
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"""
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with pytest.raises(
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ValueError, match="Can't freeze a class with a custom __setattr__."
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):
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@attr.s(auto_detect=True, slots=slots, frozen=True)
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class CustomSetAttr(Frozen):
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def __setattr__(self, _, __):
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pass
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def test_setattr_auto_detect_on_setattr(self, slots):
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"""
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on_setattr attributes together with a detected custom __setattr__ are
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rejected.
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"""
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with pytest.raises(
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ValueError,
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match="Can't combine custom __setattr__ with on_setattr hooks.",
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):
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@attr.s(auto_detect=True, slots=slots)
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class HookAndCustomSetAttr:
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x = attr.ib(on_setattr=lambda *args: None)
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def __setattr__(self, _, __):
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pass
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@pytest.mark.parametrize("a_slots", [True, False])
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@pytest.mark.parametrize("b_slots", [True, False])
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@pytest.mark.parametrize("c_slots", [True, False])
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def test_setattr_inherited_do_not_reset_intermediate(
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self, a_slots, b_slots, c_slots
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):
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"""
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A user-provided intermediate __setattr__ is not reset to
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object.__setattr__.
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This only can work with auto_detect activated, such that attrs can know
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that there is a user-provided __setattr__.
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"""
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@attr.s(slots=a_slots)
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class A:
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x = attr.ib(on_setattr=setters.frozen)
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@attr.s(slots=b_slots, auto_detect=True)
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class B(A):
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x = attr.ib(on_setattr=setters.NO_OP)
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def __setattr__(self, key, value):
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raise SystemError
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@attr.s(slots=c_slots)
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class C(B):
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pass
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assert getattr(A, "__attrs_own_setattr__", False) is True
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assert getattr(B, "__attrs_own_setattr__", False) is False
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assert getattr(C, "__attrs_own_setattr__", False) is False
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with pytest.raises(SystemError):
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C(1).x = 3
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def test_docstring(self):
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"""
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Generated __setattr__ has a useful docstring.
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"""
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assert (
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"Method generated by attrs for class WithOnSetAttrHook."
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== WithOnSetAttrHook.__setattr__.__doc__
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)
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def test_setattr_converter_piped(self):
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"""
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If a converter is used, it is piped through the on_setattr hooks.
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Regression test for https://github.com/python-attrs/attrs/issues/1327
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"""
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@attr.define # converter on setattr is implied in NG
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class C:
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x = attr.field(converter=[int])
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c = C("1")
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c.x = "2"
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assert 2 == c.x
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