Tests and helpers

tests/test_helpers.py

@@ -0,0 +1,37 @@
+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()