add daemon subcommand

This command emulates default systemd timer and can be useful in docker
container in order to run 24/7

tests/ahriman/application/handlers/test_handler_daemon.py

@@ -0,0 +1,40 @@
+import argparse
+
+from pytest_mock import MockerFixture
+
+from ahriman.application.handlers import Daemon
+from ahriman.core.configuration import Configuration
+
+
+def _default_args(args: argparse.Namespace) -> argparse.Namespace:
+    """
+    default arguments for these test cases
+
+    Args:
+        args(argparse.Namespace): command line arguments fixture
+
+    Returns:
+        argparse.Namespace: generated arguments for these test cases
+    """
+    args.interval = 60 * 60 * 12
+    args.no_aur = False
+    args.no_local = False
+    args.no_manual = False
+    args.no_vcs = False
+    return args
+
+
+def test_run(args: argparse.Namespace, configuration: Configuration, mocker: MockerFixture) -> None:
+    """
+    must run command
+    """
+    args = _default_args(args)
+    run_mock = mocker.patch("ahriman.application.handlers.Update.run")
+    start_mock = mocker.patch("threading.Timer.start")
+    join_mock = mocker.patch("threading.Timer.join")
+
+    Daemon.run(args, "x86_64", configuration, True, False)
+    Daemon._SHOULD_RUN = False
+    run_mock.assert_called_once_with(args, "x86_64", configuration, True, False)
+    start_mock.assert_called_once_with()
+    join_mock.assert_called_once_with()