New submission from Eric Engestrom <[email protected]>:
We have a pytest that boils down to the following:
```
#from __future__ import annotations
from inspect import Parameter, signature
def foo(x: str) -> str:
return x + x
def test_foo():
expected = (
Parameter("x", Parameter.POSITIONAL_OR_KEYWORD, annotation=str),
)
actual = tuple(signature(foo).parameters.values())
assert expected == actual
```
(execute with `pip install pytest && pytest -vv test_foo.py`)
I tried importing 3.10 annotations (so that we can get rid of quotes around the
class containing `foo()`, which is omitted here because it isn't necessary to
reproduce the bug), but doing so changes the output of `inspect.signature()`
but not the output `inspect.Parameter()`, causing a mismatch between the two
that breaks the test.
The above passes on 3.7.9, 3.8.7 & 3.9.1, and if I uncomment the first line, it
fails on those same versions.
As can be expected, the annotations import is a no-op on 3.10.0a5 and the test
passes either way.
I expect `inspect` might have not been correctly updated to support postponed
annotations, but I haven't looked at the implementation (I'm not familiar with
the CPython codebase at all) so it's just a guess.
----------
components: Library (Lib)
messages: 387875
nosy: 1ace
priority: normal
severity: normal
status: open
title: __future__.annotations breaks inspect.signature()
type: behavior
versions: Python 3.7, Python 3.8, Python 3.9
_______________________________________
Python tracker <[email protected]>
<https://bugs.python.org/issue43355>
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