Function validate_quantity 

pub fn validate_quantity(qty: Decimal) -> Result<()>

Validate a quantity value

Quantities must be positive (greater than zero).

Example

use stateset_core::validate_quantity;
use rust_decimal_macros::dec;

assert!(validate_quantity(dec!(1)).is_ok());
assert!(validate_quantity(dec!(0.5)).is_ok());
assert!(validate_quantity(dec!(0)).is_err());
assert!(validate_quantity(dec!(-1)).is_err());