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cpython/Lib/test/test_dataclasses.py

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# Deliberately use "from dataclasses import *". Every name in __all__
# is tested, so they all must be present. This is a way to catch
# missing ones.
from dataclasses import *
import pickle
import inspect
import builtins
import unittest
from unittest.mock import Mock
from typing import ClassVar, Any, List, Union, Tuple, Dict, Generic, TypeVar, Optional
from typing import get_type_hints
from collections import deque, OrderedDict, namedtuple
from functools import total_ordering
import typing # Needed for the string "typing.ClassVar[int]" to work as an annotation.
import dataclasses # Needed for the string "dataclasses.InitVar[int]" to work as an annotation.
# Just any custom exception we can catch.
class CustomError(Exception): pass
class TestCase(unittest.TestCase):
def test_no_fields(self):
@dataclass
class C:
pass
o = C()
self.assertEqual(len(fields(C)), 0)
def test_no_fields_but_member_variable(self):
@dataclass
class C:
i = 0
o = C()
self.assertEqual(len(fields(C)), 0)
def test_one_field_no_default(self):
@dataclass
class C:
x: int
o = C(42)
self.assertEqual(o.x, 42)
def test_field_default_default_factory_error(self):
msg = "cannot specify both default and default_factory"
with self.assertRaisesRegex(ValueError, msg):
@dataclass
class C:
x: int = field(default=1, default_factory=int)
def test_field_repr(self):
int_field = field(default=1, init=True, repr=False)
int_field.name = "id"
repr_output = repr(int_field)
expected_output = "Field(name='id',type=None," \
f"default=1,default_factory={MISSING!r}," \
"init=True,repr=False,hash=None," \
"compare=True,metadata=mappingproxy({})," \
"_field_type=None)"
self.assertEqual(repr_output, expected_output)
def test_named_init_params(self):
@dataclass
class C:
x: int
o = C(x=32)
self.assertEqual(o.x, 32)
def test_two_fields_one_default(self):
@dataclass
class C:
x: int
y: int = 0
o = C(3)
self.assertEqual((o.x, o.y), (3, 0))
# Non-defaults following defaults.
with self.assertRaisesRegex(TypeError,
"non-default argument 'y' follows "
"default argument"):
@dataclass
class C:
x: int = 0
y: int
# A derived class adds a non-default field after a default one.
with self.assertRaisesRegex(TypeError,
"non-default argument 'y' follows "
"default argument"):
@dataclass
class B:
x: int = 0
@dataclass
class C(B):
y: int
# Override a base class field and add a default to
# a field which didn't use to have a default.
with self.assertRaisesRegex(TypeError,
"non-default argument 'y' follows "
"default argument"):
@dataclass
class B:
x: int
y: int
@dataclass
class C(B):
x: int = 0
def test_overwrite_hash(self):
# Test that declaring this class isn't an error. It should
# use the user-provided __hash__.
@dataclass(frozen=True)
class C:
x: int
def __hash__(self):
return 301
self.assertEqual(hash(C(100)), 301)
# Test that declaring this class isn't an error. It should
# use the generated __hash__.
@dataclass(frozen=True)
class C:
x: int
def __eq__(self, other):
return False
self.assertEqual(hash(C(100)), hash((100,)))
# But this one should generate an exception, because with
# unsafe_hash=True, it's an error to have a __hash__ defined.
with self.assertRaisesRegex(TypeError,
'Cannot overwrite attribute __hash__'):
@dataclass(unsafe_hash=True)
class C:
def __hash__(self):
pass
# Creating this class should not generate an exception,
# because even though __hash__ exists before @dataclass is
# called, (due to __eq__ being defined), since it's None
# that's okay.
@dataclass(unsafe_hash=True)
class C:
x: int
def __eq__(self):
pass
# The generated hash function works as we'd expect.
self.assertEqual(hash(C(10)), hash((10,)))
# Creating this class should generate an exception, because
# __hash__ exists and is not None, which it would be if it
# had been auto-generated due to __eq__ being defined.
with self.assertRaisesRegex(TypeError,
'Cannot overwrite attribute __hash__'):
@dataclass(unsafe_hash=True)
class C:
x: int
def __eq__(self):
pass
def __hash__(self):
pass
def test_overwrite_fields_in_derived_class(self):
# Note that x from C1 replaces x in Base, but the order remains
# the same as defined in Base.
@dataclass
class Base:
x: Any = 15.0
y: int = 0
@dataclass
class C1(Base):
z: int = 10
x: int = 15
o = Base()
self.assertEqual(repr(o), 'TestCase.test_overwrite_fields_in_derived_class.<locals>.Base(x=15.0, y=0)')
o = C1()
self.assertEqual(repr(o), 'TestCase.test_overwrite_fields_in_derived_class.<locals>.C1(x=15, y=0, z=10)')
o = C1(x=5)
self.assertEqual(repr(o), 'TestCase.test_overwrite_fields_in_derived_class.<locals>.C1(x=5, y=0, z=10)')
def test_field_named_self(self):
@dataclass
class C:
self: str
c=C('foo')
self.assertEqual(c.self, 'foo')
# Make sure the first parameter is not named 'self'.
sig = inspect.signature(C.__init__)
first = next(iter(sig.parameters))
self.assertNotEqual('self', first)
# But we do use 'self' if no field named self.
@dataclass
class C:
selfx: str
# Make sure the first parameter is named 'self'.
sig = inspect.signature(C.__init__)
first = next(iter(sig.parameters))
self.assertEqual('self', first)
def test_field_named_object(self):
@dataclass
class C:
object: str
c = C('foo')
self.assertEqual(c.object, 'foo')
def test_field_named_object_frozen(self):
@dataclass(frozen=True)
class C:
object: str
c = C('foo')
self.assertEqual(c.object, 'foo')
def test_field_named_like_builtin(self):
# Attribute names can shadow built-in names
# since code generation is used.
# Ensure that this is not happening.
exclusions = {'None', 'True', 'False'}
builtins_names = sorted(
b for b in builtins.__dict__.keys()
if not b.startswith('__') and b not in exclusions
)
attributes = [(name, str) for name in builtins_names]
C = make_dataclass('C', attributes)
c = C(*[name for name in builtins_names])
for name in builtins_names:
self.assertEqual(getattr(c, name), name)
def test_field_named_like_builtin_frozen(self):
# Attribute names can shadow built-in names
# since code generation is used.
# Ensure that this is not happening
# for frozen data classes.
exclusions = {'None', 'True', 'False'}
builtins_names = sorted(
b for b in builtins.__dict__.keys()
if not b.startswith('__') and b not in exclusions
)
attributes = [(name, str) for name in builtins_names]
C = make_dataclass('C', attributes, frozen=True)
c = C(*[name for name in builtins_names])
for name in builtins_names:
self.assertEqual(getattr(c, name), name)
def test_0_field_compare(self):
# Ensure that order=False is the default.
@dataclass
class C0:
pass
@dataclass(order=False)
class C1:
pass
for cls in [C0, C1]:
with self.subTest(cls=cls):
self.assertEqual(cls(), cls())
for idx, fn in enumerate([lambda a, b: a < b,
lambda a, b: a <= b,
lambda a, b: a > b,
lambda a, b: a >= b]):
with self.subTest(idx=idx):
with self.assertRaisesRegex(TypeError,
f"not supported between instances of '{cls.__name__}' and '{cls.__name__}'"):
fn(cls(), cls())
@dataclass(order=True)
class C:
pass
self.assertLessEqual(C(), C())
self.assertGreaterEqual(C(), C())
def test_1_field_compare(self):
# Ensure that order=False is the default.
@dataclass
class C0:
x: int
@dataclass(order=False)
class C1:
x: int
for cls in [C0, C1]:
with self.subTest(cls=cls):
self.assertEqual(cls(1), cls(1))
self.assertNotEqual(cls(0), cls(1))
for idx, fn in enumerate([lambda a, b: a < b,
lambda a, b: a <= b,
lambda a, b: a > b,
lambda a, b: a >= b]):
with self.subTest(idx=idx):
with self.assertRaisesRegex(TypeError,
f"not supported between instances of '{cls.__name__}' and '{cls.__name__}'"):
fn(cls(0), cls(0))
@dataclass(order=True)
class C:
x: int
self.assertLess(C(0), C(1))
self.assertLessEqual(C(0), C(1))
self.assertLessEqual(C(1), C(1))
self.assertGreater(C(1), C(0))
self.assertGreaterEqual(C(1), C(0))
self.assertGreaterEqual(C(1), C(1))
def test_simple_compare(self):
# Ensure that order=False is the default.
@dataclass
class C0:
x: int
y: int
@dataclass(order=False)
class C1:
x: int
y: int
for cls in [C0, C1]:
with self.subTest(cls=cls):
self.assertEqual(cls(0, 0), cls(0, 0))
self.assertEqual(cls(1, 2), cls(1, 2))
self.assertNotEqual(cls(1, 0), cls(0, 0))
self.assertNotEqual(cls(1, 0), cls(1, 1))
for idx, fn in enumerate([lambda a, b: a < b,
lambda a, b: a <= b,
lambda a, b: a > b,
lambda a, b: a >= b]):
with self.subTest(idx=idx):
with self.assertRaisesRegex(TypeError,
f"not supported between instances of '{cls.__name__}' and '{cls.__name__}'"):
fn(cls(0, 0), cls(0, 0))
@dataclass(order=True)
class C:
x: int
y: int
for idx, fn in enumerate([lambda a, b: a == b,
lambda a, b: a <= b,
lambda a, b: a >= b]):
with self.subTest(idx=idx):
self.assertTrue(fn(C(0, 0), C(0, 0)))
for idx, fn in enumerate([lambda a, b: a < b,
lambda a, b: a <= b,
lambda a, b: a != b]):
with self.subTest(idx=idx):
self.assertTrue(fn(C(0, 0), C(0, 1)))
self.assertTrue(fn(C(0, 1), C(1, 0)))
self.assertTrue(fn(C(1, 0), C(1, 1)))
for idx, fn in enumerate([lambda a, b: a > b,
lambda a, b: a >= b,
lambda a, b: a != b]):
with self.subTest(idx=idx):
self.assertTrue(fn(C(0, 1), C(0, 0)))
self.assertTrue(fn(C(1, 0), C(0, 1)))
self.assertTrue(fn(C(1, 1), C(1, 0)))
def test_compare_subclasses(self):
# Comparisons fail for subclasses, even if no fields
# are added.
@dataclass
class B:
i: int
@dataclass
class C(B):
pass
for idx, (fn, expected) in enumerate([(lambda a, b: a == b, False),
(lambda a, b: a != b, True)]):
with self.subTest(idx=idx):
self.assertEqual(fn(B(0), C(0)), expected)
for idx, fn in enumerate([lambda a, b: a < b,
lambda a, b: a <= b,
lambda a, b: a > b,
lambda a, b: a >= b]):
with self.subTest(idx=idx):
with self.assertRaisesRegex(TypeError,
"not supported between instances of 'B' and 'C'"):
fn(B(0), C(0))
def test_eq_order(self):
# Test combining eq and order.
for (eq, order, result ) in [
(False, False, 'neither'),
(False, True, 'exception'),
(True, False, 'eq_only'),
(True, True, 'both'),
]:
with self.subTest(eq=eq, order=order):
if result == 'exception':
with self.assertRaisesRegex(ValueError, 'eq must be true if order is true'):
@dataclass(eq=eq, order=order)
class C:
pass
else:
@dataclass(eq=eq, order=order)
class C:
pass
if result == 'neither':
self.assertNotIn('__eq__', C.__dict__)
self.assertNotIn('__lt__', C.__dict__)
self.assertNotIn('__le__', C.__dict__)
self.assertNotIn('__gt__', C.__dict__)
self.assertNotIn('__ge__', C.__dict__)
elif result == 'both':
self.assertIn('__eq__', C.__dict__)
self.assertIn('__lt__', C.__dict__)
self.assertIn('__le__', C.__dict__)
self.assertIn('__gt__', C.__dict__)
self.assertIn('__ge__', C.__dict__)
elif result == 'eq_only':
self.assertIn('__eq__', C.__dict__)
self.assertNotIn('__lt__', C.__dict__)
self.assertNotIn('__le__', C.__dict__)
self.assertNotIn('__gt__', C.__dict__)
self.assertNotIn('__ge__', C.__dict__)
else:
assert False, f'unknown result {result!r}'
def test_field_no_default(self):
@dataclass
class C:
x: int = field()
self.assertEqual(C(5).x, 5)
with self.assertRaisesRegex(TypeError,
r"__init__\(\) missing 1 required "
"positional argument: 'x'"):
C()
def test_field_default(self):
default = object()
@dataclass
class C:
x: object = field(default=default)
self.assertIs(C.x, default)
c = C(10)
self.assertEqual(c.x, 10)
# If we delete the instance attribute, we should then see the
# class attribute.
del c.x
self.assertIs(c.x, default)
self.assertIs(C().x, default)
def test_not_in_repr(self):
@dataclass
class C:
x: int = field(repr=False)
with self.assertRaises(TypeError):
C()
c = C(10)
self.assertEqual(repr(c), 'TestCase.test_not_in_repr.<locals>.C()')
@dataclass
class C:
x: int = field(repr=False)
y: int
c = C(10, 20)
self.assertEqual(repr(c), 'TestCase.test_not_in_repr.<locals>.C(y=20)')
def test_not_in_compare(self):
@dataclass
class C:
x: int = 0
y: int = field(compare=False, default=4)
self.assertEqual(C(), C(0, 20))
self.assertEqual(C(1, 10), C(1, 20))
self.assertNotEqual(C(3), C(4, 10))
self.assertNotEqual(C(3, 10), C(4, 10))
def test_hash_field_rules(self):
# Test all 6 cases of:
# hash=True/False/None
# compare=True/False
for (hash_, compare, result ) in [
(True, False, 'field' ),
(True, True, 'field' ),
(False, False, 'absent'),
(False, True, 'absent'),
(None, False, 'absent'),
(None, True, 'field' ),
]:
with self.subTest(hash=hash_, compare=compare):
@dataclass(unsafe_hash=True)
class C:
x: int = field(compare=compare, hash=hash_, default=5)
if result == 'field':
# __hash__ contains the field.
self.assertEqual(hash(C(5)), hash((5,)))
elif result == 'absent':
# The field is not present in the hash.
self.assertEqual(hash(C(5)), hash(()))
else:
assert False, f'unknown result {result!r}'
def test_init_false_no_default(self):
# If init=False and no default value, then the field won't be
# present in the instance.
@dataclass
class C:
x: int = field(init=False)
self.assertNotIn('x', C().__dict__)
@dataclass
class C:
x: int
y: int = 0
z: int = field(init=False)
t: int = 10
self.assertNotIn('z', C(0).__dict__)
self.assertEqual(vars(C(5)), {'t': 10, 'x': 5, 'y': 0})
def test_class_marker(self):
@dataclass
class C:
x: int
y: str = field(init=False, default=None)
z: str = field(repr=False)
the_fields = fields(C)
# the_fields is a tuple of 3 items, each value
# is in __annotations__.
self.assertIsInstance(the_fields, tuple)
for f in the_fields:
self.assertIs(type(f), Field)
self.assertIn(f.name, C.__annotations__)
self.assertEqual(len(the_fields), 3)
self.assertEqual(the_fields[0].name, 'x')
self.assertEqual(the_fields[0].type, int)
self.assertFalse(hasattr(C, 'x'))
self.assertTrue (the_fields[0].init)
self.assertTrue (the_fields[0].repr)
self.assertEqual(the_fields[1].name, 'y')
self.assertEqual(the_fields[1].type, str)
self.assertIsNone(getattr(C, 'y'))
self.assertFalse(the_fields[1].init)
self.assertTrue (the_fields[1].repr)
self.assertEqual(the_fields[2].name, 'z')
self.assertEqual(the_fields[2].type, str)
self.assertFalse(hasattr(C, 'z'))
self.assertTrue (the_fields[2].init)
self.assertFalse(the_fields[2].repr)
def test_field_order(self):
@dataclass
class B:
a: str = 'B:a'
b: str = 'B:b'
c: str = 'B:c'
@dataclass
class C(B):
b: str = 'C:b'
self.assertEqual([(f.name, f.default) for f in fields(C)],
[('a', 'B:a'),
('b', 'C:b'),
('c', 'B:c')])
@dataclass
class D(B):
c: str = 'D:c'
self.assertEqual([(f.name, f.default) for f in fields(D)],
[('a', 'B:a'),
('b', 'B:b'),
('c', 'D:c')])
@dataclass
class E(D):
a: str = 'E:a'
d: str = 'E:d'
self.assertEqual([(f.name, f.default) for f in fields(E)],
[('a', 'E:a'),
('b', 'B:b'),
('c', 'D:c'),
('d', 'E:d')])
def test_class_attrs(self):
# We only have a class attribute if a default value is
# specified, either directly or via a field with a default.
default = object()
@dataclass
class C:
x: int
y: int = field(repr=False)
z: object = default
t: int = field(default=100)
self.assertFalse(hasattr(C, 'x'))
self.assertFalse(hasattr(C, 'y'))
self.assertIs (C.z, default)
self.assertEqual(C.t, 100)
def test_disallowed_mutable_defaults(self):
# For the known types, don't allow mutable default values.
for typ, empty, non_empty in [(list, [], [1]),
(dict, {}, {0:1}),
(set, set(), set([1])),
]:
with self.subTest(typ=typ):
# Can't use a zero-length value.
with self.assertRaisesRegex(ValueError,
f'mutable default {typ} for field '
'x is not allowed'):
@dataclass
class Point:
x: typ = empty
# Nor a non-zero-length value
with self.assertRaisesRegex(ValueError,
f'mutable default {typ} for field '
'y is not allowed'):
@dataclass
class Point:
y: typ = non_empty
# Check subtypes also fail.
class Subclass(typ): pass
with self.assertRaisesRegex(ValueError,
f"mutable default .*Subclass'>"
' for field z is not allowed'
):
@dataclass
class Point:
z: typ = Subclass()
# Because this is a ClassVar, it can be mutable.
@dataclass
class C:
z: ClassVar[typ] = typ()
# Because this is a ClassVar, it can be mutable.
@dataclass
class C:
x: ClassVar[typ] = Subclass()
def test_deliberately_mutable_defaults(self):
# If a mutable default isn't in the known list of
# (list, dict, set), then it's okay.
class Mutable:
def __init__(self):
self.l = []
@dataclass
class C:
x: Mutable
# These 2 instances will share this value of x.
lst = Mutable()
o1 = C(lst)
o2 = C(lst)
self.assertEqual(o1, o2)
o1.x.l.extend([1, 2])
self.assertEqual(o1, o2)
self.assertEqual(o1.x.l, [1, 2])
self.assertIs(o1.x, o2.x)
def test_no_options(self):
# Call with dataclass().
@dataclass()
class C:
x: int
self.assertEqual(C(42).x, 42)
def test_not_tuple(self):
# Make sure we can't be compared to a tuple.
@dataclass
class Point:
x: int
y: int
self.assertNotEqual(Point(1, 2), (1, 2))
# And that we can't compare to another unrelated dataclass.
@dataclass
class C:
x: int
y: int
self.assertNotEqual(Point(1, 3), C(1, 3))
def test_not_other_dataclass(self):
# Test that some of the problems with namedtuple don't happen
# here.
@dataclass
class Point3D:
x: int
y: int
z: int
@dataclass
class Date:
year: int
month: int
day: int
self.assertNotEqual(Point3D(2017, 6, 3), Date(2017, 6, 3))
self.assertNotEqual(Point3D(1, 2, 3), (1, 2, 3))
# Make sure we can't unpack.
with self.assertRaisesRegex(TypeError, 'unpack'):
x, y, z = Point3D(4, 5, 6)
# Make sure another class with the same field names isn't
# equal.
@dataclass
class Point3Dv1:
x: int = 0
y: int = 0
z: int = 0
self.assertNotEqual(Point3D(0, 0, 0), Point3Dv1())
def test_function_annotations(self):
# Some dummy class and instance to use as a default.
class F:
pass
f = F()
def validate_class(cls):
# First, check __annotations__, even though they're not
# function annotations.
self.assertEqual(cls.__annotations__['i'], int)
self.assertEqual(cls.__annotations__['j'], str)
self.assertEqual(cls.__annotations__['k'], F)
self.assertEqual(cls.__annotations__['l'], float)
self.assertEqual(cls.__annotations__['z'], complex)
# Verify __init__.
signature = inspect.signature(cls.__init__)
# Check the return type, should be None.
self.assertIs(signature.return_annotation, None)
# Check each parameter.
params = iter(signature.parameters.values())
param = next(params)
# This is testing an internal name, and probably shouldn't be tested.
self.assertEqual(param.name, 'self')
param = next(params)
self.assertEqual(param.name, 'i')
self.assertIs (param.annotation, int)
self.assertEqual(param.default, inspect.Parameter.empty)
self.assertEqual(param.kind, inspect.Parameter.POSITIONAL_OR_KEYWORD)
param = next(params)
self.assertEqual(param.name, 'j')
self.assertIs (param.annotation, str)
self.assertEqual(param.default, inspect.Parameter.empty)
self.assertEqual(param.kind, inspect.Parameter.POSITIONAL_OR_KEYWORD)
param = next(params)
self.assertEqual(param.name, 'k')
self.assertIs (param.annotation, F)
# Don't test for the default, since it's set to MISSING.
self.assertEqual(param.kind, inspect.Parameter.POSITIONAL_OR_KEYWORD)
param = next(params)
self.assertEqual(param.name, 'l')
self.assertIs (param.annotation, float)
# Don't test for the default, since it's set to MISSING.
self.assertEqual(param.kind, inspect.Parameter.POSITIONAL_OR_KEYWORD)
self.assertRaises(StopIteration, next, params)
@dataclass
class C:
i: int
j: str
k: F = f
l: float=field(default=None)
z: complex=field(default=3+4j, init=False)
validate_class(C)
# Now repeat with __hash__.
@dataclass(frozen=True, unsafe_hash=True)
class C:
i: int
j: str
k: F = f
l: float=field(default=None)
z: complex=field(default=3+4j, init=False)
validate_class(C)
def test_missing_default(self):
# Test that MISSING works the same as a default not being
# specified.
@dataclass
class C:
x: int=field(default=MISSING)
with self.assertRaisesRegex(TypeError,
r'__init__\(\) missing 1 required '
'positional argument'):
C()
self.assertNotIn('x', C.__dict__)
@dataclass
class D:
x: int
with self.assertRaisesRegex(TypeError,
r'__init__\(\) missing 1 required '
'positional argument'):
D()
self.assertNotIn('x', D.__dict__)
def test_missing_default_factory(self):
# Test that MISSING works the same as a default factory not
# being specified (which is really the same as a default not
# being specified, too).
@dataclass
class C:
x: int=field(default_factory=MISSING)
with self.assertRaisesRegex(TypeError,
r'__init__\(\) missing 1 required '
'positional argument'):
C()
self.assertNotIn('x', C.__dict__)
@dataclass
class D:
x: int=field(default=MISSING, default_factory=MISSING)
with self.assertRaisesRegex(TypeError,
r'__init__\(\) missing 1 required '
'positional argument'):
D()
self.assertNotIn('x', D.__dict__)
def test_missing_repr(self):
self.assertIn('MISSING_TYPE object', repr(MISSING))
def test_dont_include_other_annotations(self):
@dataclass
class C:
i: int
def foo(self) -> int:
return 4
@property
def bar(self) -> int:
return 5
self.assertEqual(list(C.__annotations__), ['i'])
self.assertEqual(C(10).foo(), 4)
self.assertEqual(C(10).bar, 5)
self.assertEqual(C(10).i, 10)
def test_post_init(self):
# Just make sure it gets called
@dataclass
class C:
def __post_init__(self):
raise CustomError()
with self.assertRaises(CustomError):
C()
@dataclass
class C:
i: int = 10
def __post_init__(self):
if self.i == 10:
raise CustomError()
with self.assertRaises(CustomError):
C()
# post-init gets called, but doesn't raise. This is just
# checking that self is used correctly.
C(5)
# If there's not an __init__, then post-init won't get called.
@dataclass(init=False)
class C:
def __post_init__(self):
raise CustomError()
# Creating the class won't raise
C()
@dataclass
class C:
x: int = 0
def __post_init__(self):
self.x *= 2
self.assertEqual(C().x, 0)
self.assertEqual(C(2).x, 4)
# Make sure that if we're frozen, post-init can't set
# attributes.
@dataclass(frozen=True)
class C:
x: int = 0
def __post_init__(self):
self.x *= 2
with self.assertRaises(FrozenInstanceError):
C()
def test_post_init_super(self):
# Make sure super() post-init isn't called by default.
class B:
def __post_init__(self):
raise CustomError()
@dataclass
class C(B):
def __post_init__(self):
self.x = 5
self.assertEqual(C().x, 5)
# Now call super(), and it will raise.
@dataclass
class C(B):
def __post_init__(self):
super().__post_init__()
with self.assertRaises(CustomError):
C()
# Make sure post-init is called, even if not defined in our
# class.
@dataclass
class C(B):
pass
with self.assertRaises(CustomError):
C()
def test_post_init_staticmethod(self):
flag = False
@dataclass
class C:
x: int
y: int
@staticmethod
def __post_init__():
nonlocal flag
flag = True
self.assertFalse(flag)
c = C(3, 4)
self.assertEqual((c.x, c.y), (3, 4))
self.assertTrue(flag)
def test_post_init_classmethod(self):
@dataclass
class C:
flag = False
x: int
y: int
@classmethod
def __post_init__(cls):
cls.flag = True
self.assertFalse(C.flag)
c = C(3, 4)
self.assertEqual((c.x, c.y), (3, 4))
self.assertTrue(C.flag)
def test_class_var(self):
# Make sure ClassVars are ignored in __init__, __repr__, etc.
@dataclass
class C:
x: int
y: int = 10
z: ClassVar[int] = 1000
w: ClassVar[int] = 2000
t: ClassVar[int] = 3000
s: ClassVar = 4000
c = C(5)
self.assertEqual(repr(c), 'TestCase.test_class_var.<locals>.C(x=5, y=10)')
self.assertEqual(len(fields(C)), 2) # We have 2 fields.
self.assertEqual(len(C.__annotations__), 6) # And 4 ClassVars.
self.assertEqual(c.z, 1000)
self.assertEqual(c.w, 2000)
self.assertEqual(c.t, 3000)
self.assertEqual(c.s, 4000)
C.z += 1
self.assertEqual(c.z, 1001)
c = C(20)
self.assertEqual((c.x, c.y), (20, 10))
self.assertEqual(c.z, 1001)
self.assertEqual(c.w, 2000)
self.assertEqual(c.t, 3000)
self.assertEqual(c.s, 4000)
def test_class_var_no_default(self):
# If a ClassVar has no default value, it should not be set on the class.
@dataclass
class C:
x: ClassVar[int]
self.assertNotIn('x', C.__dict__)
def test_class_var_default_factory(self):
# It makes no sense for a ClassVar to have a default factory. When
# would it be called? Call it yourself, since it's class-wide.
with self.assertRaisesRegex(TypeError,
'cannot have a default factory'):
@dataclass
class C:
x: ClassVar[int] = field(default_factory=int)
self.assertNotIn('x', C.__dict__)
def test_class_var_with_default(self):
# If a ClassVar has a default value, it should be set on the class.
@dataclass
class C:
x: ClassVar[int] = 10
self.assertEqual(C.x, 10)
@dataclass
class C:
x: ClassVar[int] = field(default=10)
self.assertEqual(C.x, 10)
def test_class_var_frozen(self):
# Make sure ClassVars work even if we're frozen.
@dataclass(frozen=True)
class C:
x: int
y: int = 10
z: ClassVar[int] = 1000
w: ClassVar[int] = 2000
t: ClassVar[int] = 3000
c = C(5)
self.assertEqual(repr(C(5)), 'TestCase.test_class_var_frozen.<locals>.C(x=5, y=10)')
self.assertEqual(len(fields(C)), 2) # We have 2 fields
self.assertEqual(len(C.__annotations__), 5) # And 3 ClassVars
self.assertEqual(c.z, 1000)
self.assertEqual(c.w, 2000)
self.assertEqual(c.t, 3000)
# We can still modify the ClassVar, it's only instances that are
# frozen.
C.z += 1
self.assertEqual(c.z, 1001)
c = C(20)
self.assertEqual((c.x, c.y), (20, 10))
self.assertEqual(c.z, 1001)
self.assertEqual(c.w, 2000)
self.assertEqual(c.t, 3000)
def test_init_var_no_default(self):
# If an InitVar has no default value, it should not be set on the class.
@dataclass
class C:
x: InitVar[int]
self.assertNotIn('x', C.__dict__)
def test_init_var_default_factory(self):
# It makes no sense for an InitVar to have a default factory. When
# would it be called? Call it yourself, since it's class-wide.
with self.assertRaisesRegex(TypeError,
'cannot have a default factory'):
@dataclass
class C:
x: InitVar[int] = field(default_factory=int)
self.assertNotIn('x', C.__dict__)
def test_init_var_with_default(self):
# If an InitVar has a default value, it should be set on the class.
@dataclass
class C:
x: InitVar[int] = 10
self.assertEqual(C.x, 10)
@dataclass
class C:
x: InitVar[int] = field(default=10)
self.assertEqual(C.x, 10)
def test_init_var(self):
@dataclass
class C:
x: int = None
init_param: InitVar[int] = None
def __post_init__(self, init_param):
if self.x is None:
self.x = init_param*2
c = C(init_param=10)
self.assertEqual(c.x, 20)
def test_init_var_preserve_type(self):
self.assertEqual(InitVar[int].type, int)
# Make sure the repr is correct.
self.assertEqual(repr(InitVar[int]), 'dataclasses.InitVar[int]')
self.assertEqual(repr(InitVar[List[int]]),
'dataclasses.InitVar[typing.List[int]]')
def test_init_var_inheritance(self):
# Note that this deliberately tests that a dataclass need not
# have a __post_init__ function if it has an InitVar field.
# It could just be used in a derived class, as shown here.
@dataclass
class Base:
x: int
init_base: InitVar[int]
# We can instantiate by passing the InitVar, even though
# it's not used.
b = Base(0, 10)
self.assertEqual(vars(b), {'x': 0})
@dataclass
class C(Base):
y: int
init_derived: InitVar[int]
def __post_init__(self, init_base, init_derived):
self.x = self.x + init_base
self.y = self.y + init_derived
c = C(10, 11, 50, 51)
self.assertEqual(vars(c), {'x': 21, 'y': 101})
def test_default_factory(self):
# Test a factory that returns a new list.
@dataclass
class C:
x: int
y: list = field(default_factory=list)
c0 = C(3)
c1 = C(3)
self.assertEqual(c0.x, 3)
self.assertEqual(c0.y, [])
self.assertEqual(c0, c1)
self.assertIsNot(c0.y, c1.y)
self.assertEqual(astuple(C(5, [1])), (5, [1]))
# Test a factory that returns a shared list.
l = []
@dataclass
class C:
x: int
y: list = field(default_factory=lambda: l)
c0 = C(3)
c1 = C(3)
self.assertEqual(c0.x, 3)
self.assertEqual(c0.y, [])
self.assertEqual(c0, c1)
self.assertIs(c0.y, c1.y)
self.assertEqual(astuple(C(5, [1])), (5, [1]))
# Test various other field flags.
# repr
@dataclass
class C:
x: list = field(default_factory=list, repr=False)
self.assertEqual(repr(C()), 'TestCase.test_default_factory.<locals>.C()')
self.assertEqual(C().x, [])
# hash
@dataclass(unsafe_hash=True)
class C:
x: list = field(default_factory=list, hash=False)
self.assertEqual(astuple(C()), ([],))
self.assertEqual(hash(C()), hash(()))
# init (see also test_default_factory_with_no_init)
@dataclass
class C:
x: list = field(default_factory=list, init=False)
self.assertEqual(astuple(C()), ([],))
# compare
@dataclass
class C:
x: list = field(default_factory=list, compare=False)
self.assertEqual(C(), C([1]))
def test_default_factory_with_no_init(self):
# We need a factory with a side effect.
factory = Mock()
@dataclass
class C:
x: list = field(default_factory=factory, init=False)
# Make sure the default factory is called for each new instance.
C().x
self.assertEqual(factory.call_count, 1)
C().x
self.assertEqual(factory.call_count, 2)
def test_default_factory_not_called_if_value_given(self):
# We need a factory that we can test if it's been called.
factory = Mock()
@dataclass
class C:
x: int = field(default_factory=factory)
# Make sure that if a field has a default factory function,
# it's not called if a value is specified.
C().x
self.assertEqual(factory.call_count, 1)
self.assertEqual(C(10).x, 10)
self.assertEqual(factory.call_count, 1)
C().x
self.assertEqual(factory.call_count, 2)
def test_default_factory_derived(self):
# See bpo-32896.
@dataclass
class Foo:
x: dict = field(default_factory=dict)
@dataclass
class Bar(Foo):
y: int = 1
self.assertEqual(Foo().x, {})
self.assertEqual(Bar().x, {})
self.assertEqual(Bar().y, 1)
@dataclass
class Baz(Foo):
pass
self.assertEqual(Baz().x, {})
def test_intermediate_non_dataclass(self):
# Test that an intermediate class that defines
# annotations does not define fields.
@dataclass
class A:
x: int
class B(A):
y: int
@dataclass
class C(B):
z: int
c = C(1, 3)
self.assertEqual((c.x, c.z), (1, 3))
# .y was not initialized.
with self.assertRaisesRegex(AttributeError,
'object has no attribute'):
c.y
# And if we again derive a non-dataclass, no fields are added.
class D(C):
t: int
d = D(4, 5)
self.assertEqual((d.x, d.z), (4, 5))
def test_classvar_default_factory(self):
# It's an error for a ClassVar to have a factory function.
with self.assertRaisesRegex(TypeError,
'cannot have a default factory'):
@dataclass
class C:
x: ClassVar[int] = field(default_factory=int)
def test_is_dataclass(self):
class NotDataClass:
pass
self.assertFalse(is_dataclass(0))
self.assertFalse(is_dataclass(int))
self.assertFalse(is_dataclass(NotDataClass))
self.assertFalse(is_dataclass(NotDataClass()))
@dataclass
class C:
x: int
@dataclass
class D:
d: C
e: int
c = C(10)
d = D(c, 4)
self.assertTrue(is_dataclass(C))
self.assertTrue(is_dataclass(c))
self.assertFalse(is_dataclass(c.x))
self.assertTrue(is_dataclass(d.d))
self.assertFalse(is_dataclass(d.e))
def test_is_dataclass_when_getattr_always_returns(self):
# See bpo-37868.
class A:
def __getattr__(self, key):
return 0
self.assertFalse(is_dataclass(A))
a = A()
# Also test for an instance attribute.
class B:
pass
b = B()
b.__dataclass_fields__ = []
for obj in a, b:
with self.subTest(obj=obj):
self.assertFalse(is_dataclass(obj))
# Indirect tests for _is_dataclass_instance().
with self.assertRaisesRegex(TypeError, 'should be called on dataclass instances'):
asdict(obj)
with self.assertRaisesRegex(TypeError, 'should be called on dataclass instances'):
astuple(obj)
with self.assertRaisesRegex(TypeError, 'should be called on dataclass instances'):
replace(obj, x=0)
def test_helper_fields_with_class_instance(self):
# Check that we can call fields() on either a class or instance,
# and get back the same thing.
@dataclass
class C:
x: int
y: float
self.assertEqual(fields(C), fields(C(0, 0.0)))
def test_helper_fields_exception(self):
# Check that TypeError is raised if not passed a dataclass or
# instance.
with self.assertRaisesRegex(TypeError, 'dataclass type or instance'):
fields(0)
class C: pass
with self.assertRaisesRegex(TypeError, 'dataclass type or instance'):
fields(C)
with self.assertRaisesRegex(TypeError, 'dataclass type or instance'):
fields(C())
def test_helper_asdict(self):
# Basic tests for asdict(), it should return a new dictionary.
@dataclass
class C:
x: int
y: int
c = C(1, 2)
self.assertEqual(asdict(c), {'x': 1, 'y': 2})
self.assertEqual(asdict(c), asdict(c))
self.assertIsNot(asdict(c), asdict(c))
c.x = 42
self.assertEqual(asdict(c), {'x': 42, 'y': 2})
self.assertIs(type(asdict(c)), dict)
def test_helper_asdict_raises_on_classes(self):
# asdict() should raise on a class object.
@dataclass
class C:
x: int
y: int
with self.assertRaisesRegex(TypeError, 'dataclass instance'):
asdict(C)
with self.assertRaisesRegex(TypeError, 'dataclass instance'):
asdict(int)
def test_helper_asdict_copy_values(self):
@dataclass
class C:
x: int
y: List[int] = field(default_factory=list)
initial = []
c = C(1, initial)
d = asdict(c)
self.assertEqual(d['y'], initial)
self.assertIsNot(d['y'], initial)
c = C(1)
d = asdict(c)
d['y'].append(1)
self.assertEqual(c.y, [])
def test_helper_asdict_nested(self):
@dataclass
class UserId:
token: int
group: int
@dataclass
class User:
name: str
id: UserId
u = User('Joe', UserId(123, 1))
d = asdict(u)
self.assertEqual(d, {'name': 'Joe', 'id': {'token': 123, 'group': 1}})
self.assertIsNot(asdict(u), asdict(u))
u.id.group = 2
self.assertEqual(asdict(u), {'name': 'Joe',
'id': {'token': 123, 'group': 2}})
def test_helper_asdict_builtin_containers(self):
@dataclass
class User:
name: str
id: int
@dataclass
class GroupList:
id: int
users: List[User]
@dataclass
class GroupTuple:
id: int
users: Tuple[User, ...]
@dataclass
class GroupDict:
id: int
users: Dict[str, User]
a = User('Alice', 1)
b = User('Bob', 2)
gl = GroupList(0, [a, b])
gt = GroupTuple(0, (a, b))
gd = GroupDict(0, {'first': a, 'second': b})
self.assertEqual(asdict(gl), {'id': 0, 'users': [{'name': 'Alice', 'id': 1},
{'name': 'Bob', 'id': 2}]})
self.assertEqual(asdict(gt), {'id': 0, 'users': ({'name': 'Alice', 'id': 1},
{'name': 'Bob', 'id': 2})})
self.assertEqual(asdict(gd), {'id': 0, 'users': {'first': {'name': 'Alice', 'id': 1},
'second': {'name': 'Bob', 'id': 2}}})
def test_helper_asdict_builtin_object_containers(self):
@dataclass
class Child:
d: object
@dataclass
class Parent:
child: Child
self.assertEqual(asdict(Parent(Child([1]))), {'child': {'d': [1]}})
self.assertEqual(asdict(Parent(Child({1: 2}))), {'child': {'d': {1: 2}}})
def test_helper_asdict_factory(self):
@dataclass
class C:
x: int
y: int
c = C(1, 2)
d = asdict(c, dict_factory=OrderedDict)
self.assertEqual(d, OrderedDict([('x', 1), ('y', 2)]))
self.assertIsNot(d, asdict(c, dict_factory=OrderedDict))
c.x = 42
d = asdict(c, dict_factory=OrderedDict)
self.assertEqual(d, OrderedDict([('x', 42), ('y', 2)]))
self.assertIs(type(d), OrderedDict)
def test_helper_asdict_namedtuple(self):
T = namedtuple('T', 'a b c')
@dataclass
class C:
x: str
y: T
c = C('outer', T(1, C('inner', T(11, 12, 13)), 2))
d = asdict(c)
self.assertEqual(d, {'x': 'outer',
'y': T(1,
{'x': 'inner',
'y': T(11, 12, 13)},
2),
}
)
# Now with a dict_factory. OrderedDict is convenient, but
# since it compares to dicts, we also need to have separate
# assertIs tests.
d = asdict(c, dict_factory=OrderedDict)
self.assertEqual(d, {'x': 'outer',
'y': T(1,
{'x': 'inner',
'y': T(11, 12, 13)},
2),
}
)
# Make sure that the returned dicts are actually OrderedDicts.
self.assertIs(type(d), OrderedDict)
self.assertIs(type(d['y'][1]), OrderedDict)
def test_helper_asdict_namedtuple_key(self):
# Ensure that a field that contains a dict which has a
# namedtuple as a key works with asdict().
@dataclass
class C:
f: dict
T = namedtuple('T', 'a')
c = C({T('an a'): 0})
self.assertEqual(asdict(c), {'f': {T(a='an a'): 0}})
def test_helper_asdict_namedtuple_derived(self):
class T(namedtuple('Tbase', 'a')):
def my_a(self):
return self.a
@dataclass
class C:
f: T
t = T(6)
c = C(t)
d = asdict(c)
self.assertEqual(d, {'f': T(a=6)})
# Make sure that t has been copied, not used directly.
self.assertIsNot(d['f'], t)
self.assertEqual(d['f'].my_a(), 6)
def test_helper_astuple(self):
# Basic tests for astuple(), it should return a new tuple.
@dataclass
class C:
x: int
y: int = 0
c = C(1)
self.assertEqual(astuple(c), (1, 0))
self.assertEqual(astuple(c), astuple(c))
self.assertIsNot(astuple(c), astuple(c))
c.y = 42
self.assertEqual(astuple(c), (1, 42))
self.assertIs(type(astuple(c)), tuple)
def test_helper_astuple_raises_on_classes(self):
# astuple() should raise on a class object.
@dataclass
class C:
x: int
y: int
with self.assertRaisesRegex(TypeError, 'dataclass instance'):
astuple(C)
with self.assertRaisesRegex(TypeError, 'dataclass instance'):
astuple(int)
def test_helper_astuple_copy_values(self):
@dataclass
class C:
x: int
y: List[int] = field(default_factory=list)
initial = []
c = C(1, initial)
t = astuple(c)
self.assertEqual(t[1], initial)
self.assertIsNot(t[1], initial)
c = C(1)
t = astuple(c)
t[1].append(1)
self.assertEqual(c.y, [])
def test_helper_astuple_nested(self):
@dataclass
class UserId:
token: int
group: int
@dataclass
class User:
name: str
id: UserId
u = User('Joe', UserId(123, 1))
t = astuple(u)
self.assertEqual(t, ('Joe', (123, 1)))
self.assertIsNot(astuple(u), astuple(u))
u.id.group = 2
self.assertEqual(astuple(u), ('Joe', (123, 2)))
def test_helper_astuple_builtin_containers(self):
@dataclass
class User:
name: str
id: int
@dataclass
class GroupList:
id: int
users: List[User]
@dataclass
class GroupTuple:
id: int
users: Tuple[User, ...]
@dataclass
class GroupDict:
id: int
users: Dict[str, User]
a = User('Alice', 1)
b = User('Bob', 2)
gl = GroupList(0, [a, b])
gt = GroupTuple(0, (a, b))
gd = GroupDict(0, {'first': a, 'second': b})
self.assertEqual(astuple(gl), (0, [('Alice', 1), ('Bob', 2)]))
self.assertEqual(astuple(gt), (0, (('Alice', 1), ('Bob', 2))))
self.assertEqual(astuple(gd), (0, {'first': ('Alice', 1), 'second': ('Bob', 2)}))
def test_helper_astuple_builtin_object_containers(self):
@dataclass
class Child:
d: object
@dataclass
class Parent:
child: Child
self.assertEqual(astuple(Parent(Child([1]))), (([1],),))
self.assertEqual(astuple(Parent(Child({1: 2}))), (({1: 2},),))
def test_helper_astuple_factory(self):
@dataclass
class C:
x: int
y: int
NT = namedtuple('NT', 'x y')
def nt(lst):
return NT(*lst)
c = C(1, 2)
t = astuple(c, tuple_factory=nt)
self.assertEqual(t, NT(1, 2))
self.assertIsNot(t, astuple(c, tuple_factory=nt))
c.x = 42
t = astuple(c, tuple_factory=nt)
self.assertEqual(t, NT(42, 2))
self.assertIs(type(t), NT)
def test_helper_astuple_namedtuple(self):
T = namedtuple('T', 'a b c')
@dataclass
class C:
x: str
y: T
c = C('outer', T(1, C('inner', T(11, 12, 13)), 2))
t = astuple(c)
self.assertEqual(t, ('outer', T(1, ('inner', (11, 12, 13)), 2)))
# Now, using a tuple_factory. list is convenient here.
t = astuple(c, tuple_factory=list)
self.assertEqual(t, ['outer', T(1, ['inner', T(11, 12, 13)], 2)])
def test_dynamic_class_creation(self):
cls_dict = {'__annotations__': {'x': int, 'y': int},
}
# Create the class.
cls = type('C', (), cls_dict)
# Make it a dataclass.
cls1 = dataclass(cls)
self.assertEqual(cls1, cls)
self.assertEqual(asdict(cls(1, 2)), {'x': 1, 'y': 2})
def test_dynamic_class_creation_using_field(self):
cls_dict = {'__annotations__': {'x': int, 'y': int},
'y': field(default=5),
}
# Create the class.
cls = type('C', (), cls_dict)
# Make it a dataclass.
cls1 = dataclass(cls)
self.assertEqual(cls1, cls)
self.assertEqual(asdict(cls1(1)), {'x': 1, 'y': 5})
def test_init_in_order(self):
@dataclass
class C:
a: int
b: int = field()
c: list = field(default_factory=list, init=False)
d: list = field(default_factory=list)
e: int = field(default=4, init=False)
f: int = 4
calls = []
def setattr(self, name, value):
calls.append((name, value))
C.__setattr__ = setattr
c = C(0, 1)
self.assertEqual(('a', 0), calls[0])
self.assertEqual(('b', 1), calls[1])
self.assertEqual(('c', []), calls[2])
self.assertEqual(('d', []), calls[3])
self.assertNotIn(('e', 4), calls)
self.assertEqual(('f', 4), calls[4])
def test_items_in_dicts(self):
@dataclass
class C:
a: int
b: list = field(default_factory=list, init=False)
c: list = field(default_factory=list)
d: int = field(default=4, init=False)
e: int = 0
c = C(0)
# Class dict
self.assertNotIn('a', C.__dict__)
self.assertNotIn('b', C.__dict__)
self.assertNotIn('c', C.__dict__)
self.assertIn('d', C.__dict__)
self.assertEqual(C.d, 4)
self.assertIn('e', C.__dict__)
self.assertEqual(C.e, 0)
# Instance dict
self.assertIn('a', c.__dict__)
self.assertEqual(c.a, 0)
self.assertIn('b', c.__dict__)
self.assertEqual(c.b, [])
self.assertIn('c', c.__dict__)
self.assertEqual(c.c, [])
self.assertNotIn('d', c.__dict__)
self.assertIn('e', c.__dict__)
self.assertEqual(c.e, 0)
def test_alternate_classmethod_constructor(self):
# Since __post_init__ can't take params, use a classmethod
# alternate constructor. This is mostly an example to show
# how to use this technique.
@dataclass
class C:
x: int
@classmethod
def from_file(cls, filename):
# In a real example, create a new instance
# and populate 'x' from contents of a file.
value_in_file = 20
return cls(value_in_file)
self.assertEqual(C.from_file('filename').x, 20)
def test_field_metadata_default(self):
# Make sure the default metadata is read-only and of
# zero length.
@dataclass
class C:
i: int
self.assertFalse(fields(C)[0].metadata)
self.assertEqual(len(fields(C)[0].metadata), 0)
with self.assertRaisesRegex(TypeError,
'does not support item assignment'):
fields(C)[0].metadata['test'] = 3
def test_field_metadata_mapping(self):
# Make sure only a mapping can be passed as metadata
# zero length.
with self.assertRaises(TypeError):
@dataclass
class C:
i: int = field(metadata=0)
# Make sure an empty dict works.
d = {}
@dataclass
class C:
i: int = field(metadata=d)
self.assertFalse(fields(C)[0].metadata)
self.assertEqual(len(fields(C)[0].metadata), 0)
# Update should work (see bpo-35960).
d['foo'] = 1
self.assertEqual(len(fields(C)[0].metadata), 1)
self.assertEqual(fields(C)[0].metadata['foo'], 1)
with self.assertRaisesRegex(TypeError,
'does not support item assignment'):
fields(C)[0].metadata['test'] = 3
# Make sure a non-empty dict works.
d = {'test': 10, 'bar': '42', 3: 'three'}
@dataclass
class C:
i: int = field(metadata=d)
self.assertEqual(len(fields(C)[0].metadata), 3)
self.assertEqual(fields(C)[0].metadata['test'], 10)
self.assertEqual(fields(C)[0].metadata['bar'], '42')
self.assertEqual(fields(C)[0].metadata[3], 'three')
# Update should work.
d['foo'] = 1
self.assertEqual(len(fields(C)[0].metadata), 4)
self.assertEqual(fields(C)[0].metadata['foo'], 1)
with self.assertRaises(KeyError):
# Non-existent key.
fields(C)[0].metadata['baz']
with self.assertRaisesRegex(TypeError,
'does not support item assignment'):
fields(C)[0].metadata['test'] = 3
def test_field_metadata_custom_mapping(self):
# Try a custom mapping.
class SimpleNameSpace:
def __init__(self, **kw):
self.__dict__.update(kw)
def __getitem__(self, item):
if item == 'xyzzy':
return 'plugh'
return getattr(self, item)
def __len__(self):
return self.__dict__.__len__()
@dataclass
class C:
i: int = field(metadata=SimpleNameSpace(a=10))
self.assertEqual(len(fields(C)[0].metadata), 1)
self.assertEqual(fields(C)[0].metadata['a'], 10)
with self.assertRaises(AttributeError):
fields(C)[0].metadata['b']
# Make sure we're still talking to our custom mapping.
self.assertEqual(fields(C)[0].metadata['xyzzy'], 'plugh')
def test_generic_dataclasses(self):
T = TypeVar('T')
@dataclass
class LabeledBox(Generic[T]):
content: T
label: str = '<unknown>'
box = LabeledBox(42)
self.assertEqual(box.content, 42)
self.assertEqual(box.label, '<unknown>')
# Subscripting the resulting class should work, etc.
Alias = List[LabeledBox[int]]
def test_generic_extending(self):
S = TypeVar('S')
T = TypeVar('T')
@dataclass
class Base(Generic[T, S]):
x: T
y: S
@dataclass
class DataDerived(Base[int, T]):
new_field: str
Alias = DataDerived[str]
c = Alias(0, 'test1', 'test2')
self.assertEqual(astuple(c), (0, 'test1', 'test2'))
class NonDataDerived(Base[int, T]):
def new_method(self):
return self.y
Alias = NonDataDerived[float]
c = Alias(10, 1.0)
self.assertEqual(c.new_method(), 1.0)
def test_generic_dynamic(self):
T = TypeVar('T')
@dataclass
class Parent(Generic[T]):
x: T
Child = make_dataclass('Child', [('y', T), ('z', Optional[T], None)],
bases=(Parent[int], Generic[T]), namespace={'other': 42})
self.assertIs(Child[int](1, 2).z, None)
self.assertEqual(Child[int](1, 2, 3).z, 3)
self.assertEqual(Child[int](1, 2, 3).other, 42)
# Check that type aliases work correctly.
Alias = Child[T]
self.assertEqual(Alias[int](1, 2).x, 1)
# Check MRO resolution.
self.assertEqual(Child.__mro__, (Child, Parent, Generic, object))
def test_dataclassses_pickleable(self):
global P, Q, R
@dataclass
class P:
x: int
y: int = 0
@dataclass
class Q:
x: int
y: int = field(default=0, init=False)
@dataclass
class R:
x: int
y: List[int] = field(default_factory=list)
q = Q(1)
q.y = 2
samples = [P(1), P(1, 2), Q(1), q, R(1), R(1, [2, 3, 4])]
for sample in samples:
for proto in range(pickle.HIGHEST_PROTOCOL + 1):
with self.subTest(sample=sample, proto=proto):
new_sample = pickle.loads(pickle.dumps(sample, proto))
self.assertEqual(sample.x, new_sample.x)
self.assertEqual(sample.y, new_sample.y)
self.assertIsNot(sample, new_sample)
new_sample.x = 42
another_new_sample = pickle.loads(pickle.dumps(new_sample, proto))
self.assertEqual(new_sample.x, another_new_sample.x)
self.assertEqual(sample.y, another_new_sample.y)
class TestFieldNoAnnotation(unittest.TestCase):
def test_field_without_annotation(self):
with self.assertRaisesRegex(TypeError,
"'f' is a field but has no type annotation"):
@dataclass
class C:
f = field()
def test_field_without_annotation_but_annotation_in_base(self):
@dataclass
class B:
f: int
with self.assertRaisesRegex(TypeError,
"'f' is a field but has no type annotation"):
# This is still an error: make sure we don't pick up the
# type annotation in the base class.
@dataclass
class C(B):
f = field()
def test_field_without_annotation_but_annotation_in_base_not_dataclass(self):
# Same test, but with the base class not a dataclass.
class B:
f: int
with self.assertRaisesRegex(TypeError,
"'f' is a field but has no type annotation"):
# This is still an error: make sure we don't pick up the
# type annotation in the base class.
@dataclass
class C(B):
f = field()
class TestDocString(unittest.TestCase):
def assertDocStrEqual(self, a, b):
# Because 3.6 and 3.7 differ in how inspect.signature work
# (see bpo #32108), for the time being just compare them with
# whitespace stripped.
self.assertEqual(a.replace(' ', ''), b.replace(' ', ''))
def test_existing_docstring_not_overridden(self):
@dataclass
class C:
"""Lorem ipsum"""
x: int
self.assertEqual(C.__doc__, "Lorem ipsum")
def test_docstring_no_fields(self):
@dataclass
class C:
pass
self.assertDocStrEqual(C.__doc__, "C()")
def test_docstring_one_field(self):
@dataclass
class C:
x: int
self.assertDocStrEqual(C.__doc__, "C(x:int)")
def test_docstring_two_fields(self):
@dataclass
class C:
x: int
y: int
self.assertDocStrEqual(C.__doc__, "C(x:int, y:int)")
def test_docstring_three_fields(self):
@dataclass
class C:
x: int
y: int
z: str
self.assertDocStrEqual(C.__doc__, "C(x:int, y:int, z:str)")
def test_docstring_one_field_with_default(self):
@dataclass
class C:
x: int = 3
self.assertDocStrEqual(C.__doc__, "C(x:int=3)")
def test_docstring_one_field_with_default_none(self):
@dataclass
class C:
x: Union[int, type(None)] = None
self.assertDocStrEqual(C.__doc__, "C(x:Optional[int]=None)")
def test_docstring_list_field(self):
@dataclass
class C:
x: List[int]
self.assertDocStrEqual(C.__doc__, "C(x:List[int])")
def test_docstring_list_field_with_default_factory(self):
@dataclass
class C:
x: List[int] = field(default_factory=list)
self.assertDocStrEqual(C.__doc__, "C(x:List[int]=<factory>)")
def test_docstring_deque_field(self):
@dataclass
class C:
x: deque
self.assertDocStrEqual(C.__doc__, "C(x:collections.deque)")
def test_docstring_deque_field_with_default_factory(self):
@dataclass
class C:
x: deque = field(default_factory=deque)
self.assertDocStrEqual(C.__doc__, "C(x:collections.deque=<factory>)")
class TestInit(unittest.TestCase):
def test_base_has_init(self):
class B:
def __init__(self):
self.z = 100
pass
# Make sure that declaring this class doesn't raise an error.
# The issue is that we can't override __init__ in our class,
# but it should be okay to add __init__ to us if our base has
# an __init__.
@dataclass
class C(B):
x: int = 0
c = C(10)
self.assertEqual(c.x, 10)
self.assertNotIn('z', vars(c))
# Make sure that if we don't add an init, the base __init__
# gets called.
@dataclass(init=False)
class C(B):
x: int = 10
c = C()
self.assertEqual(c.x, 10)
self.assertEqual(c.z, 100)
def test_no_init(self):
dataclass(init=False)
class C:
i: int = 0
self.assertEqual(C().i, 0)
dataclass(init=False)
class C:
i: int = 2
def __init__(self):
self.i = 3
self.assertEqual(C().i, 3)
def test_overwriting_init(self):
# If the class has __init__, use it no matter the value of
# init=.
@dataclass
class C:
x: int
def __init__(self, x):
self.x = 2 * x
self.assertEqual(C(3).x, 6)
@dataclass(init=True)
class C:
x: int
def __init__(self, x):
self.x = 2 * x
self.assertEqual(C(4).x, 8)
@dataclass(init=False)
class C:
x: int
def __init__(self, x):
self.x = 2 * x
self.assertEqual(C(5).x, 10)
class TestRepr(unittest.TestCase):
def test_repr(self):
@dataclass
class B:
x: int
@dataclass
class C(B):
y: int = 10
o = C(4)
self.assertEqual(repr(o), 'TestRepr.test_repr.<locals>.C(x=4, y=10)')
@dataclass
class D(C):
x: int = 20
self.assertEqual(repr(D()), 'TestRepr.test_repr.<locals>.D(x=20, y=10)')
@dataclass
class C:
@dataclass
class D:
i: int
@dataclass
class E:
pass
self.assertEqual(repr(C.D(0)), 'TestRepr.test_repr.<locals>.C.D(i=0)')
self.assertEqual(repr(C.E()), 'TestRepr.test_repr.<locals>.C.E()')
def test_no_repr(self):
# Test a class with no __repr__ and repr=False.
@dataclass(repr=False)
class C:
x: int
self.assertIn(f'{__name__}.TestRepr.test_no_repr.<locals>.C object at',
repr(C(3)))
# Test a class with a __repr__ and repr=False.
@dataclass(repr=False)
class C:
x: int
def __repr__(self):
return 'C-class'
self.assertEqual(repr(C(3)), 'C-class')
def test_overwriting_repr(self):
# If the class has __repr__, use it no matter the value of
# repr=.
@dataclass
class C:
x: int
def __repr__(self):
return 'x'
self.assertEqual(repr(C(0)), 'x')
@dataclass(repr=True)
class C:
x: int
def __repr__(self):
return 'x'
self.assertEqual(repr(C(0)), 'x')
@dataclass(repr=False)
class C:
x: int
def __repr__(self):
return 'x'
self.assertEqual(repr(C(0)), 'x')
class TestEq(unittest.TestCase):
def test_no_eq(self):
# Test a class with no __eq__ and eq=False.
@dataclass(eq=False)
class C:
x: int
self.assertNotEqual(C(0), C(0))
c = C(3)
self.assertEqual(c, c)
# Test a class with an __eq__ and eq=False.
@dataclass(eq=False)
class C:
x: int
def __eq__(self, other):
return other == 10
self.assertEqual(C(3), 10)
def test_overwriting_eq(self):
# If the class has __eq__, use it no matter the value of
# eq=.
@dataclass
class C:
x: int
def __eq__(self, other):
return other == 3
self.assertEqual(C(1), 3)
self.assertNotEqual(C(1), 1)
@dataclass(eq=True)
class C:
x: int
def __eq__(self, other):
return other == 4
self.assertEqual(C(1), 4)
self.assertNotEqual(C(1), 1)
@dataclass(eq=False)
class C:
x: int
def __eq__(self, other):
return other == 5
self.assertEqual(C(1), 5)
self.assertNotEqual(C(1), 1)
class TestOrdering(unittest.TestCase):
def test_functools_total_ordering(self):
# Test that functools.total_ordering works with this class.
@total_ordering
@dataclass
class C:
x: int
def __lt__(self, other):
# Perform the test "backward", just to make
# sure this is being called.
return self.x >= other
self.assertLess(C(0), -1)
self.assertLessEqual(C(0), -1)
self.assertGreater(C(0), 1)
self.assertGreaterEqual(C(0), 1)
def test_no_order(self):
# Test that no ordering functions are added by default.
@dataclass(order=False)
class C:
x: int
# Make sure no order methods are added.
self.assertNotIn('__le__', C.__dict__)
self.assertNotIn('__lt__', C.__dict__)
self.assertNotIn('__ge__', C.__dict__)
self.assertNotIn('__gt__', C.__dict__)
# Test that __lt__ is still called
@dataclass(order=False)
class C:
x: int
def __lt__(self, other):
return False
# Make sure other methods aren't added.
self.assertNotIn('__le__', C.__dict__)
self.assertNotIn('__ge__', C.__dict__)
self.assertNotIn('__gt__', C.__dict__)
def test_overwriting_order(self):
with self.assertRaisesRegex(TypeError,
'Cannot overwrite attribute __lt__'
'.*using functools.total_ordering'):
@dataclass(order=True)
class C:
x: int
def __lt__(self):
pass
with self.assertRaisesRegex(TypeError,
'Cannot overwrite attribute __le__'
'.*using functools.total_ordering'):
@dataclass(order=True)
class C:
x: int
def __le__(self):
pass
with self.assertRaisesRegex(TypeError,
'Cannot overwrite attribute __gt__'
'.*using functools.total_ordering'):
@dataclass(order=True)
class C:
x: int
def __gt__(self):
pass
with self.assertRaisesRegex(TypeError,
'Cannot overwrite attribute __ge__'
'.*using functools.total_ordering'):
@dataclass(order=True)
class C:
x: int
def __ge__(self):
pass
class TestHash(unittest.TestCase):
def test_unsafe_hash(self):
@dataclass(unsafe_hash=True)
class C:
x: int
y: str
self.assertEqual(hash(C(1, 'foo')), hash((1, 'foo')))
def test_hash_rules(self):
def non_bool(value):
# Map to something else that's True, but not a bool.
if value is None:
return None
if value:
return (3,)
return 0
def test(case, unsafe_hash, eq, frozen, with_hash, result):
with self.subTest(case=case, unsafe_hash=unsafe_hash, eq=eq,
frozen=frozen):
if result != 'exception':
if with_hash:
@dataclass(unsafe_hash=unsafe_hash, eq=eq, frozen=frozen)
class C:
def __hash__(self):
return 0
else:
@dataclass(unsafe_hash=unsafe_hash, eq=eq, frozen=frozen)
class C:
pass
# See if the result matches what's expected.
if result == 'fn':
# __hash__ contains the function we generated.
self.assertIn('__hash__', C.__dict__)
self.assertIsNotNone(C.__dict__['__hash__'])
elif result == '':
# __hash__ is not present in our class.
if not with_hash:
self.assertNotIn('__hash__', C.__dict__)
elif result == 'none':
# __hash__ is set to None.
self.assertIn('__hash__', C.__dict__)
self.assertIsNone(C.__dict__['__hash__'])
elif result == 'exception':
# Creating the class should cause an exception.
# This only happens with with_hash==True.
assert(with_hash)
with self.assertRaisesRegex(TypeError, 'Cannot overwrite attribute __hash__'):
@dataclass(unsafe_hash=unsafe_hash, eq=eq, frozen=frozen)
class C:
def __hash__(self):
return 0
else:
assert False, f'unknown result {result!r}'
# There are 8 cases of:
# unsafe_hash=True/False
# eq=True/False
# frozen=True/False
# And for each of these, a different result if
# __hash__ is defined or not.
for case, (unsafe_hash, eq, frozen, res_no_defined_hash, res_defined_hash) in enumerate([
(False, False, False, '', ''),
(False, False, True, '', ''),
(False, True, False, 'none', ''),
(False, True, True, 'fn', ''),
(True, False, False, 'fn', 'exception'),
(True, False, True, 'fn', 'exception'),
(True, True, False, 'fn', 'exception'),
(True, True, True, 'fn', 'exception'),
], 1):
test(case, unsafe_hash, eq, frozen, False, res_no_defined_hash)
test(case, unsafe_hash, eq, frozen, True, res_defined_hash)
# Test non-bool truth values, too. This is just to
# make sure the data-driven table in the decorator
# handles non-bool values.
test(case, non_bool(unsafe_hash), non_bool(eq), non_bool(frozen), False, res_no_defined_hash)
test(case, non_bool(unsafe_hash), non_bool(eq), non_bool(frozen), True, res_defined_hash)
def test_eq_only(self):
# If a class defines __eq__, __hash__ is automatically added
# and set to None. This is normal Python behavior, not
# related to dataclasses. Make sure we don't interfere with
# that (see bpo=32546).
@dataclass
class C:
i: int
def __eq__(self, other):
return self.i == other.i
self.assertEqual(C(1), C(1))
self.assertNotEqual(C(1), C(4))
# And make sure things work in this case if we specify
# unsafe_hash=True.
@dataclass(unsafe_hash=True)
class C:
i: int
def __eq__(self, other):
return self.i == other.i
self.assertEqual(C(1), C(1.0))
self.assertEqual(hash(C(1)), hash(C(1.0)))
# And check that the classes __eq__ is being used, despite
# specifying eq=True.
@dataclass(unsafe_hash=True, eq=True)
class C:
i: int
def __eq__(self, other):
return self.i == 3 and self.i == other.i
self.assertEqual(C(3), C(3))
self.assertNotEqual(C(1), C(1))
self.assertEqual(hash(C(1)), hash(C(1.0)))
def test_0_field_hash(self):
@dataclass(frozen=True)
class C:
pass
self.assertEqual(hash(C()), hash(()))
@dataclass(unsafe_hash=True)
class C:
pass
self.assertEqual(hash(C()), hash(()))
def test_1_field_hash(self):
@dataclass(frozen=True)
class C:
x: int
self.assertEqual(hash(C(4)), hash((4,)))
self.assertEqual(hash(C(42)), hash((42,)))
@dataclass(unsafe_hash=True)
class C:
x: int
self.assertEqual(hash(C(4)), hash((4,)))
self.assertEqual(hash(C(42)), hash((42,)))
def test_hash_no_args(self):
# Test dataclasses with no hash= argument. This exists to
# make sure that if the @dataclass parameter name is changed
# or the non-default hashing behavior changes, the default
# hashability keeps working the same way.
class Base:
def __hash__(self):
return 301
# If frozen or eq is None, then use the default value (do not
# specify any value in the decorator).
for frozen, eq, base, expected in [
(None, None, object, 'unhashable'),
(None, None, Base, 'unhashable'),
(None, False, object, 'object'),
(None, False, Base, 'base'),
(None, True, object, 'unhashable'),
(None, True, Base, 'unhashable'),
(False, None, object, 'unhashable'),
(False, None, Base, 'unhashable'),
(False, False, object, 'object'),
(False, False, Base, 'base'),
(False, True, object, 'unhashable'),
(False, True, Base, 'unhashable'),
(True, None, object, 'tuple'),
(True, None, Base, 'tuple'),
(True, False, object, 'object'),
(True, False, Base, 'base'),
(True, True, object, 'tuple'),
(True, True, Base, 'tuple'),
]:
with self.subTest(frozen=frozen, eq=eq, base=base, expected=expected):
# First, create the class.
if frozen is None and eq is None:
@dataclass
class C(base):
i: int
elif frozen is None:
@dataclass(eq=eq)
class C(base):
i: int
elif eq is None:
@dataclass(frozen=frozen)
class C(base):
i: int
else:
@dataclass(frozen=frozen, eq=eq)
class C(base):
i: int
# Now, make sure it hashes as expected.
if expected == 'unhashable':
c = C(10)
with self.assertRaisesRegex(TypeError, 'unhashable type'):
hash(c)
elif expected == 'base':
self.assertEqual(hash(C(10)), 301)
elif expected == 'object':
# I'm not sure what test to use here. object's
# hash isn't based on id(), so calling hash()
# won't tell us much. So, just check the
# function used is object's.
self.assertIs(C.__hash__, object.__hash__)
elif expected == 'tuple':
self.assertEqual(hash(C(42)), hash((42,)))
else:
assert False, f'unknown value for expected={expected!r}'
class TestFrozen(unittest.TestCase):
def test_frozen(self):
@dataclass(frozen=True)
class C:
i: int
c = C(10)
self.assertEqual(c.i, 10)
with self.assertRaises(FrozenInstanceError):
c.i = 5
self.assertEqual(c.i, 10)
def test_inherit(self):
@dataclass(frozen=True)
class C:
i: int
@dataclass(frozen=True)
class D(C):
j: int
d = D(0, 10)
with self.assertRaises(FrozenInstanceError):
d.i = 5
with self.assertRaises(FrozenInstanceError):
d.j = 6
self.assertEqual(d.i, 0)
self.assertEqual(d.j, 10)
# Test both ways: with an intermediate normal (non-dataclass)
# class and without an intermediate class.
def test_inherit_nonfrozen_from_frozen(self):
for intermediate_class in [True, False]:
with self.subTest(intermediate_class=intermediate_class):
@dataclass(frozen=True)
class C:
i: int
if intermediate_class:
class I(C): pass
else:
I = C
with self.assertRaisesRegex(TypeError,
'cannot inherit non-frozen dataclass from a frozen one'):
@dataclass
class D(I):
pass
def test_inherit_frozen_from_nonfrozen(self):
for intermediate_class in [True, False]:
with self.subTest(intermediate_class=intermediate_class):
@dataclass
class C:
i: int
if intermediate_class:
class I(C): pass
else:
I = C
with self.assertRaisesRegex(TypeError,
'cannot inherit frozen dataclass from a non-frozen one'):
@dataclass(frozen=True)
class D(I):
pass
def test_inherit_from_normal_class(self):
for intermediate_class in [True, False]:
with self.subTest(intermediate_class=intermediate_class):
class C:
pass
if intermediate_class:
class I(C): pass
else:
I = C
@dataclass(frozen=True)
class D(I):
i: int
d = D(10)
with self.assertRaises(FrozenInstanceError):
d.i = 5
def test_non_frozen_normal_derived(self):
# See bpo-32953.
@dataclass(frozen=True)
class D:
x: int
y: int = 10
class S(D):
pass
s = S(3)
self.assertEqual(s.x, 3)
self.assertEqual(s.y, 10)
s.cached = True
# But can't change the frozen attributes.
with self.assertRaises(FrozenInstanceError):
s.x = 5
with self.assertRaises(FrozenInstanceError):
s.y = 5
self.assertEqual(s.x, 3)
self.assertEqual(s.y, 10)
self.assertEqual(s.cached, True)
def test_overwriting_frozen(self):
# frozen uses __setattr__ and __delattr__.
with self.assertRaisesRegex(TypeError,
'Cannot overwrite attribute __setattr__'):
@dataclass(frozen=True)
class C:
x: int
def __setattr__(self):
pass
with self.assertRaisesRegex(TypeError,
'Cannot overwrite attribute __delattr__'):
@dataclass(frozen=True)
class C:
x: int
def __delattr__(self):
pass
@dataclass(frozen=False)
class C:
x: int
def __setattr__(self, name, value):
self.__dict__['x'] = value * 2
self.assertEqual(C(10).x, 20)
def test_frozen_hash(self):
@dataclass(frozen=True)
class C:
x: Any
# If x is immutable, we can compute the hash. No exception is
# raised.
hash(C(3))
# If x is mutable, computing the hash is an error.
with self.assertRaisesRegex(TypeError, 'unhashable type'):
hash(C({}))
class TestSlots(unittest.TestCase):
def test_simple(self):
@dataclass
class C:
__slots__ = ('x',)
x: Any
# There was a bug where a variable in a slot was assumed to
# also have a default value (of type
# types.MemberDescriptorType).
with self.assertRaisesRegex(TypeError,
r"__init__\(\) missing 1 required positional argument: 'x'"):
C()
# We can create an instance, and assign to x.
c = C(10)
self.assertEqual(c.x, 10)
c.x = 5
self.assertEqual(c.x, 5)
# We can't assign to anything else.
with self.assertRaisesRegex(AttributeError, "'C' object has no attribute 'y'"):
c.y = 5
def test_derived_added_field(self):
# See bpo-33100.
@dataclass
class Base:
__slots__ = ('x',)
x: Any
@dataclass
class Derived(Base):
x: int
y: int
d = Derived(1, 2)
self.assertEqual((d.x, d.y), (1, 2))
# We can add a new field to the derived instance.
d.z = 10
class TestDescriptors(unittest.TestCase):
def test_set_name(self):
# See bpo-33141.
# Create a descriptor.
class D:
def __set_name__(self, owner, name):
self.name = name + 'x'
def __get__(self, instance, owner):
if instance is not None:
return 1
return self
# This is the case of just normal descriptor behavior, no
# dataclass code is involved in initializing the descriptor.
@dataclass
class C:
c: int=D()
self.assertEqual(C.c.name, 'cx')
# Now test with a default value and init=False, which is the
# only time this is really meaningful. If not using
# init=False, then the descriptor will be overwritten, anyway.
@dataclass
class C:
c: int=field(default=D(), init=False)
self.assertEqual(C.c.name, 'cx')
self.assertEqual(C().c, 1)
def test_non_descriptor(self):
# PEP 487 says __set_name__ should work on non-descriptors.
# Create a descriptor.
class D:
def __set_name__(self, owner, name):
self.name = name + 'x'
@dataclass
class C:
c: int=field(default=D(), init=False)
self.assertEqual(C.c.name, 'cx')
def test_lookup_on_instance(self):
# See bpo-33175.
class D:
pass
d = D()
# Create an attribute on the instance, not type.
d.__set_name__ = Mock()
# Make sure d.__set_name__ is not called.
@dataclass
class C:
i: int=field(default=d, init=False)
self.assertEqual(d.__set_name__.call_count, 0)
def test_lookup_on_class(self):
# See bpo-33175.
class D:
pass
D.__set_name__ = Mock()
# Make sure D.__set_name__ is called.
@dataclass
class C:
i: int=field(default=D(), init=False)
self.assertEqual(D.__set_name__.call_count, 1)
class TestStringAnnotations(unittest.TestCase):
def test_classvar(self):
# Some expressions recognized as ClassVar really aren't. But
# if you're using string annotations, it's not an exact
# science.
# These tests assume that both "import typing" and "from
# typing import *" have been run in this file.
for typestr in ('ClassVar[int]',
'ClassVar [int]'
' ClassVar [int]',
'ClassVar',
' ClassVar ',
'typing.ClassVar[int]',
'typing.ClassVar[str]',
' typing.ClassVar[str]',
'typing .ClassVar[str]',
'typing. ClassVar[str]',
'typing.ClassVar [str]',
'typing.ClassVar [ str]',
# Not syntactically valid, but these will
# be treated as ClassVars.
'typing.ClassVar.[int]',
'typing.ClassVar+',
):
with self.subTest(typestr=typestr):
@dataclass
class C:
x: typestr
# x is a ClassVar, so C() takes no args.
C()
# And it won't appear in the class's dict because it doesn't
# have a default.
self.assertNotIn('x', C.__dict__)
def test_isnt_classvar(self):
for typestr in ('CV',
't.ClassVar',
't.ClassVar[int]',
'typing..ClassVar[int]',
'Classvar',
'Classvar[int]',
'typing.ClassVarx[int]',
'typong.ClassVar[int]',
'dataclasses.ClassVar[int]',
'typingxClassVar[str]',
):
with self.subTest(typestr=typestr):
@dataclass
class C:
x: typestr
# x is not a ClassVar, so C() takes one arg.
self.assertEqual(C(10).x, 10)
def test_initvar(self):
# These tests assume that both "import dataclasses" and "from
# dataclasses import *" have been run in this file.
for typestr in ('InitVar[int]',
'InitVar [int]'
' InitVar [int]',
'InitVar',
' InitVar ',
'dataclasses.InitVar[int]',
'dataclasses.InitVar[str]',
' dataclasses.InitVar[str]',
'dataclasses .InitVar[str]',
'dataclasses. InitVar[str]',
'dataclasses.InitVar [str]',
'dataclasses.InitVar [ str]',
# Not syntactically valid, but these will
# be treated as InitVars.
'dataclasses.InitVar.[int]',
'dataclasses.InitVar+',
):
with self.subTest(typestr=typestr):
@dataclass
class C:
x: typestr
# x is an InitVar, so doesn't create a member.
with self.assertRaisesRegex(AttributeError,
"object has no attribute 'x'"):
C(1).x
def test_isnt_initvar(self):
for typestr in ('IV',
'dc.InitVar',
'xdataclasses.xInitVar',
'typing.xInitVar[int]',
):
with self.subTest(typestr=typestr):
@dataclass
class C:
x: typestr
# x is not an InitVar, so there will be a member x.
self.assertEqual(C(10).x, 10)
def test_classvar_module_level_import(self):
from test import dataclass_module_1
from test import dataclass_module_1_str
from test import dataclass_module_2
from test import dataclass_module_2_str
for m in (dataclass_module_1, dataclass_module_1_str,
dataclass_module_2, dataclass_module_2_str,
):
with self.subTest(m=m):
# There's a difference in how the ClassVars are
# interpreted when using string annotations or
# not. See the imported modules for details.
if m.USING_STRINGS:
c = m.CV(10)
else:
c = m.CV()
self.assertEqual(c.cv0, 20)
# There's a difference in how the InitVars are
# interpreted when using string annotations or
# not. See the imported modules for details.
c = m.IV(0, 1, 2, 3, 4)
for field_name in ('iv0', 'iv1', 'iv2', 'iv3'):
with self.subTest(field_name=field_name):
with self.assertRaisesRegex(AttributeError, f"object has no attribute '{field_name}'"):
# Since field_name is an InitVar, it's
# not an instance field.
getattr(c, field_name)
if m.USING_STRINGS:
# iv4 is interpreted as a normal field.
self.assertIn('not_iv4', c.__dict__)
self.assertEqual(c.not_iv4, 4)
else:
# iv4 is interpreted as an InitVar, so it
# won't exist on the instance.
self.assertNotIn('not_iv4', c.__dict__)
def test_text_annotations(self):
from test import dataclass_textanno
self.assertEqual(
get_type_hints(dataclass_textanno.Bar),
{'foo': dataclass_textanno.Foo})
self.assertEqual(
get_type_hints(dataclass_textanno.Bar.__init__),
{'foo': dataclass_textanno.Foo,
'return': type(None)})
class TestMakeDataclass(unittest.TestCase):
def test_simple(self):
C = make_dataclass('C',
[('x', int),
('y', int, field(default=5))],
namespace={'add_one': lambda self: self.x + 1})
c = C(10)
self.assertEqual((c.x, c.y), (10, 5))
self.assertEqual(c.add_one(), 11)
def test_no_mutate_namespace(self):
# Make sure a provided namespace isn't mutated.
ns = {}
C = make_dataclass('C',
[('x', int),
('y', int, field(default=5))],
namespace=ns)
self.assertEqual(ns, {})
def test_base(self):
class Base1:
pass
class Base2:
pass
C = make_dataclass('C',
[('x', int)],
bases=(Base1, Base2))
c = C(2)
self.assertIsInstance(c, C)
self.assertIsInstance(c, Base1)
self.assertIsInstance(c, Base2)
def test_base_dataclass(self):
@dataclass
class Base1:
x: int
class Base2:
pass
C = make_dataclass('C',
[('y', int)],
bases=(Base1, Base2))
with self.assertRaisesRegex(TypeError, 'required positional'):
c = C(2)
c = C(1, 2)
self.assertIsInstance(c, C)
self.assertIsInstance(c, Base1)
self.assertIsInstance(c, Base2)
self.assertEqual((c.x, c.y), (1, 2))
def test_init_var(self):
def post_init(self, y):
self.x *= y
C = make_dataclass('C',
[('x', int),
('y', InitVar[int]),
],
namespace={'__post_init__': post_init},
)
c = C(2, 3)
self.assertEqual(vars(c), {'x': 6})
self.assertEqual(len(fields(c)), 1)
def test_class_var(self):
C = make_dataclass('C',
[('x', int),
('y', ClassVar[int], 10),
('z', ClassVar[int], field(default=20)),
])
c = C(1)
self.assertEqual(vars(c), {'x': 1})
self.assertEqual(len(fields(c)), 1)
self.assertEqual(C.y, 10)
self.assertEqual(C.z, 20)
def test_other_params(self):
C = make_dataclass('C',
[('x', int),
('y', ClassVar[int], 10),
('z', ClassVar[int], field(default=20)),
],
init=False)
# Make sure we have a repr, but no init.
self.assertNotIn('__init__', vars(C))
self.assertIn('__repr__', vars(C))
# Make sure random other params don't work.
with self.assertRaisesRegex(TypeError, 'unexpected keyword argument'):
C = make_dataclass('C',
[],
xxinit=False)
def test_no_types(self):
C = make_dataclass('Point', ['x', 'y', 'z'])
c = C(1, 2, 3)
self.assertEqual(vars(c), {'x': 1, 'y': 2, 'z': 3})
self.assertEqual(C.__annotations__, {'x': 'typing.Any',
'y': 'typing.Any',
'z': 'typing.Any'})
C = make_dataclass('Point', ['x', ('y', int), 'z'])
c = C(1, 2, 3)
self.assertEqual(vars(c), {'x': 1, 'y': 2, 'z': 3})
self.assertEqual(C.__annotations__, {'x': 'typing.Any',
'y': int,
'z': 'typing.Any'})
def test_invalid_type_specification(self):
for bad_field in [(),
(1, 2, 3, 4),
]:
with self.subTest(bad_field=bad_field):
with self.assertRaisesRegex(TypeError, r'Invalid field: '):
make_dataclass('C', ['a', bad_field])
# And test for things with no len().
for bad_field in [float,
lambda x:x,
]:
with self.subTest(bad_field=bad_field):
with self.assertRaisesRegex(TypeError, r'has no len\(\)'):
make_dataclass('C', ['a', bad_field])
def test_duplicate_field_names(self):
for field in ['a', 'ab']:
with self.subTest(field=field):
with self.assertRaisesRegex(TypeError, 'Field name duplicated'):
make_dataclass('C', [field, 'a', field])
def test_keyword_field_names(self):
for field in ['for', 'async', 'await', 'as']:
with self.subTest(field=field):
with self.assertRaisesRegex(TypeError, 'must not be keywords'):
make_dataclass('C', ['a', field])
with self.assertRaisesRegex(TypeError, 'must not be keywords'):
make_dataclass('C', [field])
with self.assertRaisesRegex(TypeError, 'must not be keywords'):
make_dataclass('C', [field, 'a'])
def test_non_identifier_field_names(self):
for field in ['()', 'x,y', '*', '2@3', '', 'little johnny tables']:
with self.subTest(field=field):
with self.assertRaisesRegex(TypeError, 'must be valid identifiers'):
make_dataclass('C', ['a', field])
with self.assertRaisesRegex(TypeError, 'must be valid identifiers'):
make_dataclass('C', [field])
with self.assertRaisesRegex(TypeError, 'must be valid identifiers'):
make_dataclass('C', [field, 'a'])
def test_underscore_field_names(self):
# Unlike namedtuple, it's okay if dataclass field names have
# an underscore.
make_dataclass('C', ['_', '_a', 'a_a', 'a_'])
def test_funny_class_names_names(self):
# No reason to prevent weird class names, since
# types.new_class allows them.
for classname in ['()', 'x,y', '*', '2@3', '']:
with self.subTest(classname=classname):
C = make_dataclass(classname, ['a', 'b'])
self.assertEqual(C.__name__, classname)
class TestReplace(unittest.TestCase):
def test(self):
@dataclass(frozen=True)
class C:
x: int
y: int
c = C(1, 2)
c1 = replace(c, x=3)
self.assertEqual(c1.x, 3)
self.assertEqual(c1.y, 2)
def test_frozen(self):
@dataclass(frozen=True)
class C:
x: int
y: int
z: int = field(init=False, default=10)
t: int = field(init=False, default=100)
c = C(1, 2)
c1 = replace(c, x=3)
self.assertEqual((c.x, c.y, c.z, c.t), (1, 2, 10, 100))
self.assertEqual((c1.x, c1.y, c1.z, c1.t), (3, 2, 10, 100))
with self.assertRaisesRegex(ValueError, 'init=False'):
replace(c, x=3, z=20, t=50)
with self.assertRaisesRegex(ValueError, 'init=False'):
replace(c, z=20)
replace(c, x=3, z=20, t=50)
# Make sure the result is still frozen.
with self.assertRaisesRegex(FrozenInstanceError, "cannot assign to field 'x'"):
c1.x = 3
# Make sure we can't replace an attribute that doesn't exist,
# if we're also replacing one that does exist. Test this
# here, because setting attributes on frozen instances is
# handled slightly differently from non-frozen ones.
with self.assertRaisesRegex(TypeError, r"__init__\(\) got an unexpected "
"keyword argument 'a'"):
c1 = replace(c, x=20, a=5)
def test_invalid_field_name(self):
@dataclass(frozen=True)
class C:
x: int
y: int
c = C(1, 2)
with self.assertRaisesRegex(TypeError, r"__init__\(\) got an unexpected "
"keyword argument 'z'"):
c1 = replace(c, z=3)
def test_invalid_object(self):
@dataclass(frozen=True)
class C:
x: int
y: int
with self.assertRaisesRegex(TypeError, 'dataclass instance'):
replace(C, x=3)
with self.assertRaisesRegex(TypeError, 'dataclass instance'):
replace(0, x=3)
def test_no_init(self):
@dataclass
class C:
x: int
y: int = field(init=False, default=10)
c = C(1)
c.y = 20
# Make sure y gets the default value.
c1 = replace(c, x=5)
self.assertEqual((c1.x, c1.y), (5, 10))
# Trying to replace y is an error.
with self.assertRaisesRegex(ValueError, 'init=False'):
replace(c, x=2, y=30)
with self.assertRaisesRegex(ValueError, 'init=False'):
replace(c, y=30)
def test_classvar(self):
@dataclass
class C:
x: int
y: ClassVar[int] = 1000
c = C(1)
d = C(2)
self.assertIs(c.y, d.y)
self.assertEqual(c.y, 1000)
# Trying to replace y is an error: can't replace ClassVars.
with self.assertRaisesRegex(TypeError, r"__init__\(\) got an "
"unexpected keyword argument 'y'"):
replace(c, y=30)
replace(c, x=5)
def test_initvar_is_specified(self):
@dataclass
class C:
x: int
y: InitVar[int]
def __post_init__(self, y):
self.x *= y
c = C(1, 10)
self.assertEqual(c.x, 10)
with self.assertRaisesRegex(ValueError, r"InitVar 'y' must be "
"specified with replace()"):
replace(c, x=3)
c = replace(c, x=3, y=5)
self.assertEqual(c.x, 15)
def test_recursive_repr(self):
@dataclass
class C:
f: "C"
c = C(None)
c.f = c
self.assertEqual(repr(c), "TestReplace.test_recursive_repr.<locals>.C(f=...)")
def test_recursive_repr_two_attrs(self):
@dataclass
class C:
f: "C"
g: "C"
c = C(None, None)
c.f = c
c.g = c
self.assertEqual(repr(c), "TestReplace.test_recursive_repr_two_attrs"
".<locals>.C(f=..., g=...)")
def test_recursive_repr_indirection(self):
@dataclass
class C:
f: "D"
@dataclass
class D:
f: "C"
c = C(None)
d = D(None)
c.f = d
d.f = c
self.assertEqual(repr(c), "TestReplace.test_recursive_repr_indirection"
".<locals>.C(f=TestReplace.test_recursive_repr_indirection"
".<locals>.D(f=...))")
def test_recursive_repr_indirection_two(self):
@dataclass
class C:
f: "D"
@dataclass
class D:
f: "E"
@dataclass
class E:
f: "C"
c = C(None)
d = D(None)
e = E(None)
c.f = d
d.f = e
e.f = c
self.assertEqual(repr(c), "TestReplace.test_recursive_repr_indirection_two"
".<locals>.C(f=TestReplace.test_recursive_repr_indirection_two"
".<locals>.D(f=TestReplace.test_recursive_repr_indirection_two"
".<locals>.E(f=...)))")
def test_recursive_repr_misc_attrs(self):
@dataclass
class C:
f: "C"
g: int
c = C(None, 1)
c.f = c
self.assertEqual(repr(c), "TestReplace.test_recursive_repr_misc_attrs"
".<locals>.C(f=..., g=1)")
## def test_initvar(self):
## @dataclass
## class C:
## x: int
## y: InitVar[int]
## c = C(1, 10)
## d = C(2, 20)
## # In our case, replacing an InitVar is a no-op
## self.assertEqual(c, replace(c, y=5))
## replace(c, x=5)
if __name__ == '__main__':
unittest.main()
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