import pytest
from datetime import datetime, timedelta
from src.utils import parse_relative_expression, parse_date_string

def test_parse_relative_expression_days():
    # Test T, T+n, T-n
    result = parse_relative_expression("T")
    assert result is not None
    assert isinstance(result, datetime)
    
    result_plus = parse_relative_expression("T+5")
    assert result_plus is not None
    
    result_minus = parse_relative_expression("T-3")
    assert result_minus is not None

def test_parse_relative_expression_invalid():
    assert parse_relative_expression("abc") is None
    assert parse_relative_expression("123") is None
    assert parse_relative_expression("T++1") is None

def test_parse_date_string_formats():
    # Test various ISO and common formats
    dt = parse_date_string("2024-11-08")
    assert dt.year == 2024
    assert dt.month == 11
    assert dt.day == 8
    
    dt = parse_date_string("08-11-2024")
    assert dt.year == 2024
    assert dt.month == 11
    assert dt.day == 8

def test_parse_date_string_invalid():
    with pytest.raises(ValueError):
        parse_date_string("invalid-date")