import unittest
from utils.helpers import format_currency, format_date, validate_pin, parse_price

class TestHelpers(unittest.TestCase):
    def test_format_currency_german(self):
        self.assertEqual(format_currency(2.50), "2,50 €")
        self.assertEqual(format_currency(1234.567), "1234,57 €")
        self.assertEqual(format_currency(0.0), "0,00 €")

    def test_format_currency_non_german(self):
        self.assertEqual(format_currency(2.50, symbol="$", is_german=False), "$2.50")
        self.assertEqual(format_currency(0.99, symbol="£", is_german=False), "£0.99")

    def test_format_date(self):
        self.assertEqual(format_date("2026-06-02T15:00:00.000000"), "02.06.2026")
        self.assertEqual(format_date("2026-12-25T18:30:00"), "25.12.2026")
        self.assertEqual(format_date("invalid-date-format"), "invalid-da")

    def test_validate_pin(self):
        self.assertTrue(validate_pin("1234"))
        self.assertTrue(validate_pin("4242"))
        self.assertTrue(validate_pin("123456"))
        self.assertFalse(validate_pin("123"))  # too short
        self.assertFalse(validate_pin("123a")) # non-numeric
        self.assertFalse(validate_pin(""))     # empty

    def test_parse_price(self):
        self.assertEqual(parse_price("2.50"), 2.50)
        self.assertEqual(parse_price("2,50"), 2.50)
        self.assertEqual(parse_price(" 0,99 "), 0.99)
        with self.assertRaises(ValueError):
            parse_price("-2.50") # negative
        with self.assertRaises(ValueError):
            parse_price("abc")   # non-numeric

if __name__ == "__main__":
    unittest.main()