Python 3.8 introduced the typing.TypedDict type to properly annotate dicts with multiple types. It appears that this type is not compatible with the type annotations for monkeypatch.setitem.

The following code runs fine with pytest:

from typing import TypedDict

from _pytest.monkeypatch import MonkeyPatch

Foo = TypedDict('Foo', {'x': int, 'y': float})

a: Foo = {'x': 1, 'y': 3.14}
b = {'x': 1, 'y': 3.14}

def test(monkeypatch: MonkeyPatch) -> None:
    monkeypatch.setitem(a, 'x', 2)
    monkeypatch.setitem(b, 'x', 2)

However, it fails with mypy:

$ mypy test.py
test.py:11: error: Argument 1 to "setitem" of "MonkeyPatch" has incompatible type "Foo"; expected "MutableMapping[str, int]"  [arg-type]
Found 1 error in 1 file (checked 1 source file)

Versions

• Python 3.10.10
• pytest 7.2.1
• macOS 13.3.1 (a)