def test_attendee_birthday_calendar(
            self,
            admin_attendee,
            year,
            birthdays,
            monkeypatch):

        if year:
            assert str(year)
            response = summary.Root().attendee_birthday_calendar(year=year)
        else:
            assert str(datetime.now(UTC).year)
            response = summary.Root().attendee_birthday_calendar()
        if isinstance(response, bytes):
            response = response.decode('utf-8')

        lines = response.strip().split('\n')
        assert len(lines) == (17 + 1)  # Extra line for the header