def METHOD_NAME(mocker, api_isc_mock, reset_singleton):
    # Arrange
    isc.MANAGER = None
    manager = isc.get_manager(api_isc_mock)
    mocked_restart = mocker.patch.object(
        manager, "restart_dhcp", autospec=True, return_value=0
    )
    mocked_service_name = mocker.patch(
        "cobbler.utils.dhcp_service_name", autospec=True, return_value="dhcpd"
    )
    # Act
    result = manager.restart_service()
    # Assert
    assert mocked_service_name.call_count == 1
    assert mocked_restart.call_count == 2
    assert result == 0