[Python] How to make mypy ignore pytest.approx in a code outside of test functions

I want to use pytest.approx(...) inside immutable dataclasses (frozen=True) in my unittest, so I can use a single assert to check possibly quite complex structures.

This works fine when I use these structures inside test functions, but when I declare a global variable/constant which uses approx, I get an error in mypy.

Example code:

from pytest import approx
from typing import Final
from dataclasses import dataclass

@dataclass(frozen=True)
class A:
x: float


EXPECTED_VALUE_1: Final = A(approx(0.5)) # <- this is the problem

def test_1():
assert A(0.5) == EXPECTED_VALUE_1

def test_2():
expected_value_2 = A(approx(0.5)) # <- this is fine
assert A(0.5) == expected_value_2


The error:

$ mypy .
a.py:10: error: Argument 1 to "A" has incompatible type "ApproxBase"; expected "float" [arg-type]
Found 1 error in 1 file (checked 1 source file)


I think I know why - mypy by default ignores untyped functions (and my unittest functions are all untyped), but outside those functions it checks.

I've found 2 solutions:

1. add # type: ignore where this happens - which is in my opinion ugly and makes the code less readable
2. using pytest.fixture in place of a global constant. But in many cases, I have a lot of these EXPECTED_... constants (which are using approx) and converting them to fixtures makes code a lot longer and less readable, so, for simple, immutable data, I would like to keep using these global constants.

Can I somehow configure mypy to just ignore every call to approx and check everything else?

Configuration:

• 
  Python 3.10.16
  
  
• 
  mypy 1.16.0
  
  
• 
  mypy configuration:
  
  [mypy]
  python_version = 3.10
  ignore_missing_imports = True

Suggested solutions/duplicate questions:

• How can mypy ignore a single line in a source file? - this is dealing with ignoring one line of code by adding a # type: ignore, which is something I wrote in "What I tried" section I know about and that it's not a solution I want. I want a solution where I would, if possible, change mypy config or somehow "patch" approx so mypy would ignore just the approx calls but otherwise check typing errors.

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