# 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 unittest from unittest.mock import Mock from typing import ClassVar, Any, List, Union, Tuple, Dict, Generic, TypeVar, Optional 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_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..Base(x=15.0, y=0)') o = C1() self.assertEqual(repr(o), 'TestCase.test_overwrite_fields_in_derived_class..C1(x=15, y=0, z=10)') o = C1(x=5) self.assertEqual(repr(o), 'TestCase.test_overwrite_fields_in_derived_class..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_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..C()') @dataclass class C: x: int = field(repr=False) y: int c = C(10, 20) self.assertEqual(repr(c), 'TestCase.test_not_in_repr..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_tuple(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..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..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_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..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_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_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_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_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_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. @dataclass class C: i: int = field(metadata={}) 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 # Make sure a non-empty dict works. @dataclass class C: i: int = field(metadata={'test': 10, 'bar': '42', 3: 'three'}) 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') 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 = '' box = LabeledBox(42) self.assertEqual(box.content, 42) self.assertEqual(box.label, '') # 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:Union[int, NoneType]=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]=)") 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=)") 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..C(x=4, y=10)') @dataclass class D(C): x: int = 20 self.assertEqual(repr(D()), 'TestRepr.test_repr..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..C.D(i=0)') self.assertEqual(repr(C.E()), 'TestRepr.test_repr..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('test_dataclasses.TestRepr.test_no_repr..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 . import dataclass_module_1 from . import dataclass_module_1_str from . import dataclass_module_2 from . 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__) 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 identifers'): make_dataclass('C', ['a', field]) with self.assertRaisesRegex(TypeError, 'must be valid identifers'): make_dataclass('C', [field]) with self.assertRaisesRegex(TypeError, 'must be valid identifers'): 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_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()