add new type alias for db_factory fixture

src/ensembl/utils/plugin.py

@@ -20,7 +20,7 @@
 import os
 from pathlib import Path
 import re
-from typing import Callable, Generator
+from typing import Callable, Generator, TypeAlias
 
 import pytest
 from pytest import Config, FixtureRequest, Parser
@@ -30,6 +30,9 @@
 from ensembl.utils.database import UnitTestDB
 
 
+DBFactory: TypeAlias = Callable[[StrPath | None, str | None, MetaData | None], UnitTestDB]
+
+
 def pytest_addoption(parser: Parser) -> None:
     """Registers argparse-style options for Ensembl's unit testing.
 
@@ -115,7 +118,7 @@ def _assert_files(result_path: StrPath, expected_path: StrPath) -> None:
 
 
 @pytest.fixture(name="db_factory", scope="module")
-def fixture_db_factory(request: FixtureRequest, data_dir: Path) -> Generator[Callable, None, None]:
+def fixture_db_factory(request: FixtureRequest, data_dir: Path) -> Generator[DBFactory, None, None]:
     """Yields a unit test database factory.
 
     Args: