[BUG] auth/AuthProvider type hint incorrect

[huwcbjones]

Checklist

• I checked the FAQ section of the documentation
• I looked for similar issues in the issue tracker

Describe the bug
I believe the type hint for AuthProvider is incorrect.
The definition of AuthProvider uses a TypeVar for the data argument to get and set.
I think the intended behaviour was to mandate that the types passed to get and set are the same for a given AuthProvider.

To Reproduce
Steps to reproduce the behavior:

1. Implement an Auth Provider (see example below):

from typing import Any

import schemathesis
from schemathesis import Case
from schemathesis.auths import AuthProvider, AuthContext

@schemathesis.auth
class Provider(AuthProvider):
    def get(self, context: AuthContext) -> dict[str, Any]:
        return {"access_token": "foo"}
    def set(self, case: Case, data: dict[str, Any], context: AuthContext) -> None:
        reveal_type(data)

2. Run mypy mwe.py
3. Get errors about liskov subsitution policy

$ mypy mwe.py
mwe.py:11: error: Return type "Dict[str, Any]" of "get" incompatible with return type "Optional[Auth]" in supertype "AuthProvider"  [override]
mwe.py:14: error: Argument 2 of "set" is incompatible with supertype "AuthProvider"; supertype defines the argument type as "Auth"  [override]
mwe.py:14: note: This violates the Liskov substitution principle
mwe.py:14: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
mwe.py:15: note: Revealed type is "builtins.dict[builtins.str, Any]"
Found 2 errors in 1 file (checked 1 source file)

Expected behavior
No mypy errors

Environment (please complete the following information):

• OS: Linux or macOS
• Python version: 3.9.2
• Schemathesis version: 3.17.9
• Spec version: N/A

Additional context
If I add Generic[Auth] to the AuthProvider class definition, the errors go away.

--- a/src/schemathesis/auths.py
+++ b/src/schemathesis/auths.py
@@ -32,7 +32,7 @@


 @runtime_checkable
-class AuthProvider(Protocol):
+class AuthProvider(Protocol, Generic[Auth]):
     """Get authentication data for an API and set it on the generated test cases."""

     def get(self, context: AuthContext) -> Optional[Auth]:

[huwcbjones]

Apologies, didn't quite fully fix this one.

New error is now

mwe.py:7:2: error: Argument 1 to "__call__" of "FilterableApplyAuth" has incompatible type "Type[Provider]"; expected "Callable[..., None]"  [arg-type]
mwe.py:12:21: note: Revealed type is "builtins.dict[builtins.str, Any]"
Found 1 error in 1 file (checked 1 source file)

[Stranger6667]

Oh, what mypy version are you using?

[huwcbjones]

Workaround is to use @schemathesis.auth.register() instead of @schemathesis.auth()

[huwcbjones]

Oh, what mypy version are you using?

1.0.1 as it's the current version in Debian (stable) Bookworm

[huwcbjones]

Can still reproduce the above mypy error on 1.5.1 (latest as of writing)