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v/vlib/rand/random_bytes_test.v

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import rand
fn test_rand_bytes() ? {
mut randoms := []string{}
for i in 0 .. 100 {
x := rand.bytes(i) ?.hex()
if x.len > 0 {
randoms << x
}
assert x.len == i * 2
}
mut differences := 0
for idx in 1 .. randoms.len {
start := randoms[idx]#[0..8]
prev_start := randoms[idx - 1]#[0..8]
if start != prev_start {
differences++
}
}
assert differences > 95 // normally around 98
dump(differences)
}
fn test_rand_read() ? {
max := 50
mut a := []byte{len: max}
mut differences := 0
for j in 1 .. max {
start := '00'.repeat(j)
for k in j + 1 .. max {
end := '00'.repeat(max - k)
middle := '00'.repeat(k - j)
// eprintln('> j: $j | k: $k | start: $start | middle: $middle | end: $end')
for i in 0 .. max {
a[i] = 0
}
assert a[j..k].hex() == middle
for i in 0 .. 10 {
rand.read(mut a[j..k])
// dump(a.hex())
assert a[0..j].hex() == start
assert a[k..].hex() == end
if a[j..k].hex() != middle {
differences++
}
}
}
}
dump(differences)
assert differences > 11700 // normally around 11758
}