def METHOD_NAME(harness):
    outbox_tester = OutboxTester(harness)
    result, received_notifications = outbox_tester.get_notifications()
    assert result, "Failed to get notifications!"
    assert not received_notifications, "Notification list is not empty at the beginning of the test!"
    # Add message to generate "message created" and "thread created" notifications
    message_number = "123456789"
    message_body = "Hello, how are you?"
    result, message_record = outbox_tester.add_message(message_number, message_body)
    assert result, "Failed to add message!"
    # Add contact to generate "contact created" notification
    contact_record = {
        "address": "6 Czeczota St.\n02600 Warsaw",
        "altName": "Smith",
        "email": "john.smith@mudita.com",
        "blocked": False,
        "favourite": False,
        "ice": False,
        "numbers": [
            "123456789"
        ],
        "speedDial": "1",
        "priName": "John",
        "note": "Some note"
    }
    result, contact_id = outbox_tester.add_contact(contact_record)
    assert result, "Failed to add contact!"
    result, received_notifications = outbox_tester.get_notifications()
    assert result, "Failed to get notifications!"
    uids_of_notifications_to_be_deleted = []
    for notification in received_notifications:
        uids_of_notifications_to_be_deleted.append(notification.uid)
    result = outbox_tester.delete_notifications(uids_of_notifications_to_be_deleted)
    assert result, "Failed to get notifications!"
    # Check if all generated notifications are deleted
    result, received_notifications = outbox_tester.get_notifications()
    assert result, "Failed to get notifications!"
    for notification in received_notifications:
        assert notification.uid not in uids_of_notifications_to_be_deleted, "Notification not deleted!"
    assert outbox_tester.delete_message_by_id(message_record["messageID"]), "Failed to delete a message!"
    assert outbox_tester.delete_contact_by_id(contact_id), "Failed to delete a contact!"