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import pytest
import astroid
from astroid import bases, nodes
from astroid.const import PY37_PLUS
from astroid.exceptions import InferenceError
from astroid.util import Uninferable
if not PY37_PLUS:
pytest.skip("Dataclasses were added in 3.7", allow_module_level=True)
def test_inference_attribute_no_default():
"""Test inference of dataclass attribute with no default.
Note that the argument to the constructor is ignored by the inference.
"""
klass, instance = astroid.extract_node(
"""
from dataclasses import dataclass
@dataclass
class A:
name: str
A.name #@
A('hi').name #@
"""
)
with pytest.raises(InferenceError):
klass.inferred()
inferred = instance.inferred()
assert len(inferred) == 1
assert isinstance(inferred[0], bases.Instance)
assert inferred[0].name == "str"
def test_inference_non_field_default():
"""Test inference of dataclass attribute with a non-field default."""
klass, instance = astroid.extract_node(
"""
from dataclasses import dataclass
@dataclass
class A:
name: str = 'hi'
A.name #@
A().name #@
"""
)
inferred = klass.inferred()
assert len(inferred) == 1
assert isinstance(inferred[0], nodes.Const)
assert inferred[0].value == "hi"
inferred = instance.inferred()
assert len(inferred) == 2
assert isinstance(inferred[0], nodes.Const)
assert inferred[0].value == "hi"
assert isinstance(inferred[1], bases.Instance)
assert inferred[1].name == "str"
def test_inference_field_default():
"""Test inference of dataclass attribute with a field call default
(default keyword argument given)."""
klass, instance = astroid.extract_node(
"""
from dataclasses import dataclass, field
@dataclass
class A:
name: str = field(default='hi')
A.name #@
A().name #@
"""
)
inferred = klass.inferred()
assert len(inferred) == 1
assert isinstance(inferred[0], nodes.Const)
assert inferred[0].value == "hi"
inferred = instance.inferred()
assert len(inferred) == 2
assert isinstance(inferred[0], nodes.Const)
assert inferred[0].value == "hi"
assert isinstance(inferred[1], bases.Instance)
assert inferred[1].name == "str"
def test_inference_field_default_factory():
"""Test inference of dataclass attribute with a field call default
(default_factory keyword argument given)."""
klass, instance = astroid.extract_node(
"""
from dataclasses import dataclass, field
@dataclass
class A:
name: list = field(default_factory=list)
A.name #@
A().name #@
"""
)
inferred = klass.inferred()
assert len(inferred) == 1
assert isinstance(inferred[0], nodes.List)
assert inferred[0].elts == []
inferred = instance.inferred()
assert len(inferred) == 2
assert isinstance(inferred[0], nodes.List)
assert inferred[0].elts == []
assert isinstance(inferred[1], bases.Instance)
assert inferred[1].name == "list"
def test_inference_method():
"""Test inference of dataclass attribute within a method,
with a default_factory field.
Based on https://github.com/PyCQA/pylint/issues/2600
"""
node = astroid.extract_node(
"""
from typing import Dict
from dataclasses import dataclass, field
@dataclass
class TestClass:
foo: str
bar: str
baz_dict: Dict[str, str] = field(default_factory=dict)
def some_func(self) -> None:
f = self.baz_dict.items #@
for key, value in f():
print(key)
print(value)
"""
)
inferred = next(node.value.infer())
assert isinstance(inferred, bases.BoundMethod)
def test_inference_no_annotation():
"""Test that class variables without type annotations are not
turned into instance attributes.
"""
class_def, klass, instance = astroid.extract_node(
"""
from dataclasses import dataclass
@dataclass
class A:
name = 'hi'
A #@
A.name #@
A().name #@
"""
)
inferred = next(class_def.infer())
assert isinstance(inferred, nodes.ClassDef)
assert inferred.instance_attrs == {}
# Both the class and instance can still access the attribute
for node in (klass, instance):
inferred = node.inferred()
assert len(inferred) == 1
assert isinstance(inferred[0], nodes.Const)
assert inferred[0].value == "hi"
def test_inference_class_var():
"""Test that class variables with a ClassVar type annotations are not
turned into instance attributes.
"""
class_def, klass, instance = astroid.extract_node(
"""
from dataclasses import dataclass
from typing import ClassVar
@dataclass
class A:
name: ClassVar[str] = 'hi'
A #@
A.name #@
A().name #@
"""
)
inferred = next(class_def.infer())
assert isinstance(inferred, nodes.ClassDef)
assert inferred.instance_attrs == {}
# Both the class and instance can still access the attribute
for node in (klass, instance):
inferred = node.inferred()
assert len(inferred) == 1
assert isinstance(inferred[0], nodes.Const)
assert inferred[0].value == "hi"
def test_inference_init_var():
"""Test that class variables with InitVar type annotations are not
turned into instance attributes.
"""
class_def, klass, instance = astroid.extract_node(
"""
from dataclasses import dataclass, InitVar
@dataclass
class A:
name: InitVar[str] = 'hi'
A #@
A.name #@
A().name #@
"""
)
inferred = next(class_def.infer())
assert isinstance(inferred, nodes.ClassDef)
assert inferred.instance_attrs == {}
# Both the class and instance can still access the attribute
for node in (klass, instance):
inferred = node.inferred()
assert len(inferred) == 1
assert isinstance(inferred[0], nodes.Const)
assert inferred[0].value == "hi"
def test_inference_generic_collection_attribute():
"""Test that an attribute with a generic collection type from the
typing module is inferred correctly.
"""
attr_nodes = astroid.extract_node(
"""
from dataclasses import dataclass, field
import typing
@dataclass
class A:
dict_prop: typing.Dict[str, str]
frozenset_prop: typing.FrozenSet[str]
list_prop: typing.List[str]
set_prop: typing.Set[str]
tuple_prop: typing.Tuple[int, str]
a = A({}, frozenset(), [], set(), (1, 'hi'))
a.dict_prop #@
a.frozenset_prop #@
a.list_prop #@
a.set_prop #@
a.tuple_prop #@
"""
)
names = (
"Dict",
"FrozenSet",
"List",
"Set",
"Tuple",
)
for node, name in zip(attr_nodes, names):
inferred = next(node.infer())
assert isinstance(inferred, bases.Instance)
assert inferred.name == name
def test_inference_callable_attribute():
"""Test that an attribute with a Callable annotation is inferred as Uninferable.
See issue#1129.
"""
instance = astroid.extract_node(
"""
from dataclasses import dataclass
from typing import Any, Callable
@dataclass
class A:
enabled: Callable[[Any], bool]
A(lambda x: x == 42).enabled #@
"""
)
inferred = next(instance.infer())
assert inferred is Uninferable
|
