type checking fixes

src/blueapi/service/authentication.py

@@ -61,7 +61,7 @@ def print_user_info(self, token: str) -> None:
 
 class TokenManager(ABC):
     @abstractmethod
-    def save_token(self, token: dict[str, Any]): ...
+    def save_token(self, token: dict[str, Any]) -> None: ...
     @abstractmethod
     def load_token(token) -> dict[str, Any] | None: ...
     @abstractmethod
@@ -119,6 +119,7 @@ def from_config(
                     client_config,
                     CLITokenManager(Path(client_config.token_file_path)),
                 )
+        return None
 
     def get_token(self) -> dict[str, Any] | None:
         return self._token_manager.load_token()
@@ -139,19 +140,21 @@ def refresh_auth_token(self) -> dict[str, Any] | None:
             )
             if response.status_code == HTTPStatus.OK:
                 token = response.json()
-                self._token_manager.save_token(token)
-                return token
+                if token:
+                    self._token_manager.save_token(token)
+                    return token
+        return None
 
     def get_device_code(self):
-        response: requests.Response = requests.post(
+        response = requests.post(
             self._server_config.token_url,
             data={
                 "client_id": self._client_config.client_id,
                 "scope": "openid profile offline_access",
                 "audience": self._client_config.client_audience,
             },
         )
-        response_data: dict[str, str] = response.json()
+        response_data = response.json()
         if response.status_code == 200:
             return response_data["device_code"]
         raise Exception("Failed to get device code.")

tests/unit_tests/service/test_authentication.py

@@ -39,9 +39,10 @@ def mock_server_config(mock_requests_get) -> OAuthServerConfig:
 
 
 @pytest.fixture
-def mock_session_manager(mock_client_config, mock_server_config) -> SessionManager:
-    session_manager = SessionManager.from_config(mock_server_config, mock_client_config)
-    return session_manager
+def mock_session_manager(
+    mock_client_config: OAuthClientConfig, mock_server_config: OAuthServerConfig
+) -> SessionManager | None:
+    return SessionManager.from_config(mock_server_config, mock_client_config)
 
 
 @pytest.fixture