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bpo-38605: Make 'from __future__ import annotations' the default (GH-20434)

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The hard part was making all the tests pass; there are some subtle issues here, because apparently the future import wasn't tested very thoroughly in previous Python versions.

For example, `inspect.signature()` returned type objects normally (except for forward references), but strings with the future import. We changed it to try and return type objects by calling `typing.get_type_hints()`, but fall back on returning strings if that function fails (which it may do if there are future references in the annotations that require passing in a specific namespace to resolve).
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Batuhan Taskaya 2020-10-06 23:03:02 +03:00 • committed by GitHub
parent bef7d299eb
commit 044a1048ca
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27 changed files with 403 additions and 299 deletions
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79
Lib/test/test_dataclasses.py
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@ -9,6 +9,7 @@ import pickle
import inspect
import builtins
import unittest
from textwrap import dedent
from unittest.mock import Mock
from typing import ClassVar, Any, List, Union, Tuple, Dict, Generic, TypeVar, Optional
from typing import get_type_hints
@ -562,17 +563,17 @@ class TestCase(unittest.TestCase):
self.assertEqual(len(the_fields), 3)
self.assertEqual(the_fields[0].name, 'x')
self.assertEqual(the_fields[0].type, int)
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.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.assertEqual(the_fields[2].type, 'str')
self.assertFalse(hasattr(C, 'z'))
self.assertTrue (the_fields[2].init)
self.assertFalse(the_fields[2].repr)
@ -758,11 +759,11 @@ class TestCase(unittest.TestCase):
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)
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__.
@ -777,22 +778,22 @@ class TestCase(unittest.TestCase):
self.assertEqual(param.name, 'self')
param = next(params)
self.assertEqual(param.name, 'i')
self.assertIs (param.annotation, int)
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.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)
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)
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)
@ -2806,13 +2807,10 @@ class TestDescriptors(unittest.TestCase):
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 [int]',
'ClassVar',
' ClassVar ',
@ -2823,17 +2821,15 @@ class TestStringAnnotations(unittest.TestCase):
'typing. ClassVar[str]',
'typing.ClassVar [str]',
'typing.ClassVar [ str]',
# Double stringified
'"typing.ClassVar[int]"',
# Not syntactically valid, but these will
# be treated as ClassVars.
# be treated as ClassVars.
'typing.ClassVar.[int]',
'typing.ClassVar+',
):
with self.subTest(typestr=typestr):
@dataclass
class C:
x: typestr
C = dataclass(type("C", (), {"__annotations__": {"x": typestr}}))
# x is a ClassVar, so C() takes no args.
C()
@ -2854,9 +2850,7 @@ class TestStringAnnotations(unittest.TestCase):
'typingxClassVar[str]',
):
with self.subTest(typestr=typestr):
@dataclass
class C:
x: typestr
C = dataclass(type("C", (), {"__annotations__": {"x": typestr}}))
# x is not a ClassVar, so C() takes one arg.
self.assertEqual(C(10).x, 10)
@ -2876,16 +2870,16 @@ class TestStringAnnotations(unittest.TestCase):
'dataclasses. InitVar[str]',
'dataclasses.InitVar [str]',
'dataclasses.InitVar [ str]',
# Double stringified
'"dataclasses.InitVar[int]"',
# 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
C = dataclass(type("C", (), {"__annotations__": {"x": typestr}}))
# x is an InitVar, so doesn't create a member.
with self.assertRaisesRegex(AttributeError,
@ -2899,30 +2893,22 @@ class TestStringAnnotations(unittest.TestCase):
'typing.xInitVar[int]',
):
with self.subTest(typestr=typestr):
@dataclass
class C:
x: typestr
C = dataclass(type("C", (), {"__annotations__": {"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,
):
for m in (dataclass_module_1,
dataclass_module_2):
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()
c = m.CV(10)
self.assertEqual(c.cv0, 20)
@ -2938,14 +2924,9 @@ class TestStringAnnotations(unittest.TestCase):
# 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__)
# iv4 is interpreted as a normal field.
self.assertIn('not_iv4', c.__dict__)
self.assertEqual(c.not_iv4, 4)
def test_text_annotations(self):
from test import dataclass_textanno