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# SPDX-License-Identifier: MIT
"""
Tests for PEP-526 type annotations.
Python 3.6+ only.
"""
import sys
import types
import typing
import pytest
import attr
from attr._make import _is_class_var
from attr.exceptions import UnannotatedAttributeError
def assert_init_annotations(cls, **annotations):
"""
Assert cls.__init__ has the correct annotations.
"""
__tracebackhide__ = True
annotations["return"] = type(None)
assert annotations == typing.get_type_hints(cls.__init__)
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.resolve_types
@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_init_annotations(C, x=int, y=str)
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.resolve_types
@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_init_annotations(C, x=typing.List[int], y=typing.Optional[str])
def test_only_attrs_annotations_collected(self):
"""
Annotations that aren't set to an attr.ib are ignored.
"""
@attr.resolve_types
@attr.s
class C:
x: typing.List[int] = attr.ib()
y: int
assert 1 == len(attr.fields(C))
assert_init_annotations(C, x=typing.List[int])
@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
attr.resolve_types(C)
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_init_annotations(
C,
a=int,
x=typing.List[int],
y=int,
z=int,
foo=typing.Optional[typing.Any],
)
@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.resolve_types
@attr.s(slots=slots, auto_attribs=True)
class A:
a: int = 1
@attr.resolve_types
@attr.s(slots=slots, auto_attribs=True)
class B(A):
b: int = 2
@attr.resolve_types
@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_init_annotations(A, a=int)
assert_init_annotations(B, a=int, b=int)
assert_init_annotations(C, a=int)
def test_converter_annotations(self):
"""
An unannotated attribute with an annotated converter gets its
annotation from the converter.
"""
def int2str(x: int) -> str:
return str(x)
@attr.s
class A:
a = attr.ib(converter=int2str)
assert_init_annotations(A, a=int)
def int2str_(x: int, y: str = ""):
return str(x)
@attr.s
class A:
a = attr.ib(converter=int2str_)
assert_init_annotations(A, a=int)
def test_converter_attrib_annotations(self):
"""
If a converter is provided, an explicit type annotation has no
effect on an attribute's type annotation.
"""
def int2str(x: int) -> str:
return str(x)
@attr.s
class A:
a: str = attr.ib(converter=int2str)
b = attr.ib(converter=int2str, type=str)
assert_init_annotations(A, a=int, b=int)
def test_non_introspectable_converter(self):
"""
A non-introspectable converter doesn't cause a crash.
"""
@attr.s
class A:
a = attr.ib(converter=print)
def test_nullary_converter(self):
"""
A coverter with no arguments doesn't cause a crash.
"""
def noop():
pass
@attr.s
class A:
a = attr.ib(converter=noop)
assert A.__init__.__annotations__ == {"return": None}
def test_pipe(self):
"""
pipe() uses the input annotation of its first argument and the
output annotation of its last argument.
"""
def int2str(x: int) -> str:
return str(x)
def strlen(y: str) -> int:
return len(y)
def identity(z):
return z
assert attr.converters.pipe(int2str).__annotations__ == {
"val": int,
"return": str,
}
assert attr.converters.pipe(int2str, strlen).__annotations__ == {
"val": int,
"return": int,
}
assert attr.converters.pipe(identity, strlen).__annotations__ == {
"return": int
}
assert attr.converters.pipe(int2str, identity).__annotations__ == {
"val": int
}
def int2str_(x: int, y: int = 0) -> str:
return str(x)
assert attr.converters.pipe(int2str_).__annotations__ == {
"val": int,
"return": str,
}
def test_pipe_empty(self):
"""
pipe() with no converters is annotated like the identity.
"""
p = attr.converters.pipe()
assert "val" in p.__annotations__
t = p.__annotations__["val"]
assert isinstance(t, typing.TypeVar)
assert p.__annotations__ == {"val": t, "return": t}
def test_pipe_non_introspectable(self):
"""
pipe() doesn't crash when passed a non-introspectable converter.
"""
assert attr.converters.pipe(print).__annotations__ == {}
def test_pipe_nullary(self):
"""
pipe() doesn't crash when passed a nullary converter.
"""
def noop():
pass
assert attr.converters.pipe(noop).__annotations__ == {}
def test_optional(self):
"""
optional() uses the annotations of the converter it wraps.
"""
def int2str(x: int) -> str:
return str(x)
def int_identity(x: int):
return x
def strify(x) -> str:
return str(x)
def identity(x):
return x
assert attr.converters.optional(int2str).__annotations__ == {
"val": typing.Optional[int],
"return": typing.Optional[str],
}
assert attr.converters.optional(int_identity).__annotations__ == {
"val": typing.Optional[int]
}
assert attr.converters.optional(strify).__annotations__ == {
"return": typing.Optional[str]
}
assert attr.converters.optional(identity).__annotations__ == {}
def int2str_(x: int, y: int = 0) -> str:
return str(x)
assert attr.converters.optional(int2str_).__annotations__ == {
"val": typing.Optional[int],
"return": typing.Optional[str],
}
def test_optional_non_introspectable(self):
"""
optional() doesn't crash when passed a non-introspectable
converter.
"""
assert attr.converters.optional(print).__annotations__ == {}
def test_optional_nullary(self):
"""
optional() doesn't crash when passed a nullary converter.
"""
def noop():
pass
assert attr.converters.optional(noop).__annotations__ == {}
@pytest.mark.xfail(
sys.version_info[:2] == (3, 6), reason="Does not work on 3.6."
)
@pytest.mark.parametrize("slots", [True, False])
def test_annotations_strings(self, slots):
"""
String annotations are passed into __init__ as is.
It fails on 3.6 due to a bug in Python.
"""
import typing as t
from typing import ClassVar
@attr.s(auto_attribs=True, slots=slots)
class C:
cls_var1: "typing.ClassVar[int]" = 23
cls_var2: "ClassVar[int]" = 23
cls_var3: "t.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
attr.resolve_types(C, locals(), globals())
assert_init_annotations(
C,
a=int,
x=typing.List[int],
y=int,
z=int,
foo=typing.Optional[typing.Any],
)
@pytest.mark.parametrize("slots", [True, False])
def test_typing_extensions_classvar(self, slots):
"""
If ClassVar is coming from typing_extensions, it is recognized too.
"""
@attr.s(auto_attribs=True, slots=slots)
class C:
cls_var: "typing_extensions.ClassVar" = 23 # noqa
assert_init_annotations(C)
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
def test_removes_none_too(self):
"""
Regression test for #523: make sure defaults that are set to None are
removed too.
"""
@attr.s(auto_attribs=True)
class C:
x: int = 42
y: typing.Any = None
with pytest.raises(AttributeError):
C.x
with pytest.raises(AttributeError):
C.y
def test_non_comparable_defaults(self):
"""
Regression test for #585: objects that are not directly comparable
(for example numpy arrays) would cause a crash when used as
default values of an attrs auto-attrib class.
"""
class NonComparable:
def __eq__(self, other):
raise ValueError
@attr.s(auto_attribs=True)
class C:
x: typing.Any = NonComparable()
def test_basic_resolve(self):
"""
Resolve the `Attribute.type` attr from basic type annotations.
Unannotated types are ignored.
"""
@attr.s
class C:
x: "int" = attr.ib()
y = attr.ib(type=str)
z = attr.ib()
attr.resolve_types(C)
assert int is attr.fields(C).x.type
assert str is attr.fields(C).y.type
assert None is attr.fields(C).z.type
@pytest.mark.parametrize("slots", [True, False])
def test_resolve_types_auto_attrib(self, slots):
"""
Types can be resolved even when strings are involved.
"""
@attr.s(slots=slots, auto_attribs=True)
class A:
a: typing.List[int]
b: typing.List["int"]
c: "typing.List[int]"
# Note: I don't have to pass globals and locals here because
# int is a builtin and will be available in any scope.
attr.resolve_types(A)
assert typing.List[int] == attr.fields(A).a.type
assert typing.List[int] == attr.fields(A).b.type
assert typing.List[int] == attr.fields(A).c.type
@pytest.mark.parametrize("slots", [True, False])
def test_resolve_types_decorator(self, slots):
"""
Types can be resolved using it as a decorator.
"""
@attr.resolve_types
@attr.s(slots=slots, auto_attribs=True)
class A:
a: typing.List[int]
b: typing.List["int"]
c: "typing.List[int]"
assert typing.List[int] == attr.fields(A).a.type
assert typing.List[int] == attr.fields(A).b.type
assert typing.List[int] == attr.fields(A).c.type
@pytest.mark.parametrize("slots", [True, False])
def test_self_reference(self, slots):
"""
References to self class using quotes can be resolved.
"""
@attr.s(slots=slots, auto_attribs=True)
class A:
a: "A"
b: typing.Optional["A"] # noqa: will resolve below
attr.resolve_types(A, globals(), locals())
assert A == attr.fields(A).a.type
assert typing.Optional[A] == attr.fields(A).b.type
@pytest.mark.parametrize("slots", [True, False])
def test_forward_reference(self, slots):
"""
Forward references can be resolved.
"""
@attr.s(slots=slots, auto_attribs=True)
class A:
a: typing.List["B"] # noqa: will resolve below
@attr.s(slots=slots, auto_attribs=True)
class B:
a: A
attr.resolve_types(A, globals(), locals())
attr.resolve_types(B, globals(), locals())
assert typing.List[B] == attr.fields(A).a.type
assert A == attr.fields(B).a.type
assert typing.List[B] == attr.fields(A).a.type
assert A == attr.fields(B).a.type
def test_init_type_hints(self):
"""
Forward references in __init__ can be automatically resolved.
"""
@attr.s
class C:
x = attr.ib(type="typing.List[int]")
assert_init_annotations(C, x=typing.List[int])
def test_init_type_hints_fake_module(self):
"""
If you somehow set the __module__ to something that doesn't exist
you'll lose __init__ resolution.
"""
class C:
x = attr.ib(type="typing.List[int]")
C.__module__ = "totally fake"
C = attr.s(C)
with pytest.raises(NameError):
typing.get_type_hints(C.__init__)
def test_inheritance(self):
"""
Subclasses can be resolved after the parent is resolved.
"""
@attr.define()
class A:
n: "int"
@attr.define()
class B(A):
pass
attr.resolve_types(A)
attr.resolve_types(B)
assert int == attr.fields(A).n.type
assert int == attr.fields(B).n.type
def test_resolve_twice(self):
"""
You can call resolve_types as many times as you like.
This test is here mostly for coverage.
"""
@attr.define()
class A:
n: "int"
attr.resolve_types(A)
assert int == attr.fields(A).n.type
attr.resolve_types(A)
assert int == attr.fields(A).n.type
@pytest.mark.parametrize(
"annot",
[
typing.ClassVar,
"typing.ClassVar",
"'typing.ClassVar[dict]'",
"t.ClassVar[int]",
],
)
def test_is_class_var(annot):
"""
ClassVars are detected, even if they're a string or quoted.
"""
assert _is_class_var(annot)