const n = 1000

const c = 100

fn f(ch chan int) {
    for _ in 0 .. n {
        _ := <-ch
    }
    ch.close()
}

fn test_push_or_unbuffered() {
    ch := chan int{}
    spawn f(ch)
    mut j := 0
    for {
        ch <- j or { break }

        j++
    }
    assert j == n
}

fn test_push_or_buffered() {
    ch := chan int{cap: c}
    spawn f(ch)
    mut j := 0
    for {
        ch <- j or { break }

        j++
    }
    // we don't know how many elements are in the buffer when the channel
    // is closed, so check j against an interval
    assert j >= n
    assert j <= n + c
}

fn g(ch chan int, res chan int) {
    mut j := 0
    for {
        ch <- j or { break }

        j++
    }
    println('done ${j}')
    res <- j
}

fn test_many_senders() {
    ch := chan int{}
    res := chan int{}
    spawn g(ch, res)
    spawn g(ch, res)
    spawn g(ch, res)
    mut k := 0
    for _ in 0 .. 3 * n {
        k = <-ch
    }
    ch.close()
    mut sum := <-res
    sum += <-res
    sum += <-res
    assert sum == 3 * n
}