import time

fn do_rec_i64(ch chan i64) {
    mut sum := i64(0)
    for _ in 0 .. 300 {
        sum += <-ch
    }
    assert sum == 300 * (300 - 1) / 2
}

fn do_send_int(ch chan int) {
    for i in 0 .. 300 {
        ch <- i
    }
}

fn do_send_u8(ch chan u8) {
    for i in 0 .. 300 {
        ch <- u8(i)
    }
}

fn do_send_i64(ch chan i64) {
    for i in 0 .. 300 {
        ch <- i
    }
}

fn test_select() {
    chi := chan int{}
    chl := chan i64{cap: 1}
    chb := chan u8{cap: 10}
    recch := chan i64{cap: 0}
    spawn do_rec_i64(recch)
    spawn do_send_int(chi)
    spawn do_send_u8(chb)
    spawn do_send_i64(chl)
    mut sum := i64(0)
    mut rl := i64(0)
    mut sl := i64(0)
    for _ in 0 .. 1200 {
        select {
            ri := <-chi {
                sum += ri
            }
            recch <- sl {
                sl++
            }
            rl = <-chl {
                sum += rl
            }
            rb := <-chb {
                sum += rb
            }
        }
    }
    // Use Gauß' formula for the first 2 contributions
    // the 3rd contribution is `byte` and must be seen modulo 256
    expected_sum := 2 * (300 * (300 - 1) / 2) + 256 * (256 - 1) / 2 + 44 * (44 - 1) / 2
    assert sum == expected_sum
    time.sleep(20 * time.millisecond) // to give assert in coroutine enough time
}