Also test typing.NamedTuple with copy.replace

[sobolevn]

Bug report

Right now only collections.namedtuple is tested:

cpython/Lib/test/test_copy.py

Lines 937 to 946 in b1aebf1

	def test_namedtuple(self):
	from collections import namedtuple
	Point = namedtuple('Point', 'x y', defaults=(0,))
	p = Point(11, 22)
	self.assertEqual(copy.replace(p), (11, 22))
	self.assertEqual(copy.replace(p, x=1), (1, 22))
	self.assertEqual(copy.replace(p, y=2), (11, 2))
	self.assertEqual(copy.replace(p, x=1, y=2), (1, 2))
	with self.assertRaisesRegex(ValueError, 'unexpected field name'):
	copy.replace(p, x=1, error=2)

@serhiy-storchaka noted in #108752 (comment) that only named tuples created by collections.namedtuple() are supported. But, since typing.NamedTuple uses collections.namedtuple inside:

cpython/Lib/typing.py

Lines 2695 to 2696 in b1aebf1

	nm_tpl = collections.namedtuple(name, fields,
	defaults=defaults, module=module)

it is also supported:

>>> import typing
>>> 
>>> class N(typing.NamedTuple):
...    x: int
...    y: int
... 
>>> N.__replace__
<function N._replace at 0x10580a210>
>>> import copy
>>> copy.replace(N(1, 2), x=3)
N(x=3, y=2)

I have a PR ready with extra tests.

Refs #108751
Refs #108752

Linked PRs

• gh-109956: Also test typing.NamedTuple with copy.replace #109957

[serhiy-storchaka]

"Named tuple" is more general term (https://docs.python.org/3/glossary.html#term-named-tuple). Not all named tuples in wide meaning are supported (for example named tuples created by the PyStructSequence C API are not supported yet). typing.NamedTyple is a funny way to call collections.namedtuple(), so this note covers it too. If you want to test them, would not be better to add new tests to other typing.NamedTyple tests?