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"""
Tests for PEP-526 type annotations.
Python 3.6+ only.
"""
import types
import typing
import pytest
import attr
from attr._make import _classvar_prefixes
from attr.exceptions import UnannotatedAttributeError
class TestAnnotations:
"""
Tests for types derived from variable annotations (PEP-526).
"""
def test_basic_annotations(self):
"""
Sets the `Attribute.type` attr from basic type annotations.
"""
@attr.s
class C:
x: int = attr.ib()
y = attr.ib(type=str)
z = attr.ib()
assert int is attr.fields(C).x.type
assert str is attr.fields(C).y.type
assert None is attr.fields(C).z.type
assert C.__init__.__annotations__ == {
"x": int,
"y": str,
"return": None,
}
def test_catches_basic_type_conflict(self):
"""
Raises ValueError if type is specified both ways.
"""
with pytest.raises(ValueError) as e:
@attr.s
class C:
x: int = attr.ib(type=int)
assert (
"Type annotation and type argument cannot both be present",
) == e.value.args
def test_typing_annotations(self):
"""
Sets the `Attribute.type` attr from typing annotations.
"""
@attr.s
class C:
x: typing.List[int] = attr.ib()
y = attr.ib(type=typing.Optional[str])
assert typing.List[int] is attr.fields(C).x.type
assert typing.Optional[str] is attr.fields(C).y.type
assert C.__init__.__annotations__ == {
"x": typing.List[int],
"y": typing.Optional[str],
"return": None,
}
def test_only_attrs_annotations_collected(self):
"""
Annotations that aren't set to an attr.ib are ignored.
"""
@attr.s
class C:
x: typing.List[int] = attr.ib()
y: int
assert 1 == len(attr.fields(C))
assert C.__init__.__annotations__ == {
"x": typing.List[int],
"return": None,
}
@pytest.mark.parametrize("slots", [True, False])
def test_auto_attribs(self, slots):
"""
If *auto_attribs* is True, bare annotations are collected too.
Defaults work and class variables are ignored.
"""
@attr.s(auto_attribs=True, slots=slots)
class C:
cls_var: typing.ClassVar[int] = 23
a: int
x: typing.List[int] = attr.Factory(list)
y: int = 2
z: int = attr.ib(default=3)
foo: typing.Any = None
i = C(42)
assert "C(a=42, x=[], y=2, z=3, foo=None)" == repr(i)
attr_names = set(a.name for a in C.__attrs_attrs__)
assert "a" in attr_names # just double check that the set works
assert "cls_var" not in attr_names
assert int == attr.fields(C).a.type
assert attr.Factory(list) == attr.fields(C).x.default
assert typing.List[int] == attr.fields(C).x.type
assert int == attr.fields(C).y.type
assert 2 == attr.fields(C).y.default
assert int == attr.fields(C).z.type
assert typing.Any == attr.fields(C).foo.type
# Class body is clean.
if slots is False:
with pytest.raises(AttributeError):
C.y
assert 2 == i.y
else:
assert isinstance(C.y, types.MemberDescriptorType)
i.y = 23
assert 23 == i.y
assert C.__init__.__annotations__ == {
"a": int,
"x": typing.List[int],
"y": int,
"z": int,
"foo": typing.Any,
"return": None,
}
@pytest.mark.parametrize("slots", [True, False])
def test_auto_attribs_unannotated(self, slots):
"""
Unannotated `attr.ib`s raise an error.
"""
with pytest.raises(UnannotatedAttributeError) as e:
@attr.s(slots=slots, auto_attribs=True)
class C:
v = attr.ib()
x: int
y = attr.ib()
z: str
assert (
"The following `attr.ib`s lack a type annotation: v, y.",
) == e.value.args
@pytest.mark.parametrize("slots", [True, False])
def test_auto_attribs_subclassing(self, slots):
"""
Attributes from base classes are inherited, it doesn't matter if the
subclass has annotations or not.
Ref #291
"""
@attr.s(slots=slots, auto_attribs=True)
class A:
a: int = 1
@attr.s(slots=slots, auto_attribs=True)
class B(A):
b: int = 2
@attr.s(slots=slots, auto_attribs=True)
class C(A):
pass
assert "B(a=1, b=2)" == repr(B())
assert "C(a=1)" == repr(C())
assert A.__init__.__annotations__ == {"a": int, "return": None}
assert B.__init__.__annotations__ == {
"a": int,
"b": int,
"return": None,
}
assert C.__init__.__annotations__ == {"a": int, "return": None}
def test_converter_annotations(self):
"""
Attributes with converters don't have annotations.
"""
@attr.s(auto_attribs=True)
class A:
a: int = attr.ib(converter=int)
assert A.__init__.__annotations__ == {"return": None}
@pytest.mark.parametrize("slots", [True, False])
@pytest.mark.parametrize("classvar", _classvar_prefixes)
def test_annotations_strings(self, slots, classvar):
"""
String annotations are passed into __init__ as is.
"""
@attr.s(auto_attribs=True, slots=slots)
class C:
cls_var: classvar + "[int]" = 23
a: "int"
x: "typing.List[int]" = attr.Factory(list)
y: "int" = 2
z: "int" = attr.ib(default=3)
foo: "typing.Any" = None
assert C.__init__.__annotations__ == {
"a": "int",
"x": "typing.List[int]",
"y": "int",
"z": "int",
"foo": "typing.Any",
"return": None,
}
def test_keyword_only_auto_attribs(self):
"""
`kw_only` propagates to attributes defined via `auto_attribs`.
"""
@attr.s(auto_attribs=True, kw_only=True)
class C:
x: int
y: int
with pytest.raises(TypeError):
C(0, 1)
with pytest.raises(TypeError):
C(x=0)
c = C(x=0, y=1)
assert c.x == 0
assert c.y == 1
def test_base_class_variable(self):
"""
Base class' class variables can be overridden with an attribute
without resorting to using an explicit `attr.ib()`.
"""
class Base:
x: int = 42
@attr.s(auto_attribs=True)
class C(Base):
x: int
assert 1 == C(1).x
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