Tests and helpers

utils/helpers.py

@@ -0,0 +1,34 @@
+import re
+
+def format_currency(amount: float, symbol: str = "€", is_german: bool = True) -> str:
+    """Formats a numeric amount to a currency string representation."""
+    if is_german:
+        return f"{amount:.2f}".replace(".", ",") + f" {symbol}"
+    else:
+        return f"{symbol}{amount:.2f}"
+
+def format_date(iso_timestamp: str) -> str:
+    """Converts ISO timestamp to German date format DD.MM.YYYY."""
+    try:
+        date_part = iso_timestamp.split("T")[0]
+        parts = date_part.split("-")
+        if len(parts) == 3 and all(p.isdigit() for p in parts) and len(parts[0]) == 4:
+            return f"{parts[2]}.{parts[1]}.{parts[0]}"
+    except Exception:
+        pass
+    return iso_timestamp[:10]
+
+
+def validate_pin(pin: str) -> bool:
+    """Validates that a PIN consists of at least 4 numeric digits."""
+    return bool(re.match(r"^\d{4,}$", pin))
+
+def parse_price(price_str: str) -> float:
+    """Parses a string containing a price (handling comma and dot) to a float.
+    Raises ValueError if invalid.
+    """
+    clean_str = price_str.replace(",", ".").strip()
+    price = float(clean_str)
+    if price < 0:
+        raise ValueError("Price cannot be negative")
+    return price