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v/vlib/rand/sys/system_rng_test.v

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import math
import rand
import rand.sys
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const (
range_limit = 40
value_count = 1000
seeds = [u32(42), 256]
)
const (
sample_size = 1000
stats_epsilon = 0.05
inv_sqrt_12 = 1.0 / math.sqrt(12)
)
fn get_n_randoms(n int, mut r rand.PRNG) []int {
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mut ints := []int{cap: n}
for _ in 0 .. n {
ints << r.int()
}
return ints
}
fn test_sys_rng_reproducibility() {
// Note that C.srand() sets the seed globally.
// So the order of seeding matters. It is recommended
// to obtain all necessary data first, then set the
// seed for another batch of data.
for seed in seeds {
seed_data := [seed]
mut r1 := &rand.PRNG(&sys.SysRNG{})
mut r2 := &rand.PRNG(&sys.SysRNG{})
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r1.seed(seed_data)
ints1 := get_n_randoms(value_count, mut r1)
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r2.seed(seed_data)
ints2 := get_n_randoms(value_count, mut r2)
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assert ints1 == ints2
}
}
fn test_sys_rng_variability() {
// If this test fails and if it is certainly not the implementation
// at fault, try changing the seed values. Repeated values are
// improbable but not impossible.
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
mut values := []u64{cap: value_count}
for i in 0 .. value_count {
value := rng.u64()
assert value !in values
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assert values.len == i
values << value
}
}
}
fn check_uniformity_u64(mut rng rand.PRNG, range u64) {
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range_f64 := f64(range)
expected_mean := range_f64 / 2.0
mut variance := 0.0
for _ in 0 .. sample_size {
diff := f64(rng.u64n(range) or { panic("Couldn't obtain u64") }) - expected_mean
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variance += diff * diff
}
variance /= sample_size - 1
sigma := math.sqrt(variance)
expected_sigma := range_f64 * inv_sqrt_12
error := (sigma - expected_sigma) / expected_sigma
assert math.abs(error) < stats_epsilon
}
fn test_sys_rng_uniformity_u64() {
// This assumes that C.rand() produces uniform results to begin with.
// If the failure persists, report an issue on GitHub
ranges := [14019545, 80240, 130]
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for range in ranges {
check_uniformity_u64(mut rng, u64(range))
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}
}
}
fn check_uniformity_f64(mut rng rand.PRNG) {
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expected_mean := 0.5
mut variance := 0.0
for _ in 0 .. sample_size {
diff := rng.f64() - expected_mean
variance += diff * diff
}
variance /= sample_size - 1
sigma := math.sqrt(variance)
expected_sigma := inv_sqrt_12
error := (sigma - expected_sigma) / expected_sigma
assert math.abs(error) < stats_epsilon
}
fn test_sys_rng_uniformity_f64() {
// The f64 version
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
check_uniformity_f64(mut rng)
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}
}
fn test_sys_rng_u32n() {
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max := u32(16384)
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for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.u32n(max) or { panic("Couldn't obtain u32") }
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assert value >= 0
assert value < max
}
}
}
fn test_sys_rng_u64n() {
max := u64(379091181005)
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.u64n(max) or { panic("Couldn't obtain u64") }
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assert value >= 0
assert value < max
}
}
}
fn test_sys_rng_u32_in_range() {
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max := u32(484468466)
min := u32(316846)
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for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.u32_in_range(min, max) or { panic("Couldn't obtain u32 in range") }
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assert value >= min
assert value < max
}
}
}
fn test_sys_rng_u64_in_range() {
max := u64(216468454685163)
min := u64(6848646868)
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.u64_in_range(min, max) or { panic("Couldn't obtain u64 in range") }
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assert value >= min
assert value < max
}
}
}
fn test_sys_rng_intn() {
max := 2525642
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.intn(max) or { panic("Couldn't obtain int") }
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assert value >= 0
assert value < max
}
}
}
fn test_sys_rng_i64n() {
max := i64(3246727724653636)
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.i64n(max) or { panic("Couldn't obtain i64") }
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assert value >= 0
assert value < max
}
}
}
fn test_sys_rng_int_in_range() {
min := -4252
max := 23054962
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.int_in_range(min, max) or { panic("Couldn't obtain int in range") }
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assert value >= min
assert value < max
}
}
}
fn test_sys_rng_i64_in_range() {
min := i64(-24095)
max := i64(324058)
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.i64_in_range(min, max) or { panic("Couldn't obtain i64 in range") }
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assert value >= min
assert value < max
}
}
}
fn test_sys_rng_int31() {
max_u31 := int(0x7FFFFFFF)
sign_mask := int(0x80000000)
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for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.int31()
assert value >= 0
assert value <= max_u31
// This statement ensures that the sign bit is zero
assert (value & sign_mask) == 0
}
}
}
fn test_sys_rng_int63() {
max_u63 := i64(0x7FFFFFFFFFFFFFFF)
sign_mask := i64(0x8000000000000000)
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.int63()
assert value >= 0
assert value <= max_u63
assert (value & sign_mask) == 0
}
}
}
fn test_sys_rng_f32() {
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.f32()
assert value >= 0.0
assert value < 1.0
}
}
}
fn test_sys_rng_f64() {
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.f64()
assert value >= 0.0
assert value < 1.0
}
}
}
fn test_sys_rng_f32n() {
max := f32(357.0)
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.f32n(max) or { panic("Couldn't obtain f32") }
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assert value >= 0.0
assert value < max
}
}
}
fn test_sys_rng_f64n() {
max := 1.52e6
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.f64n(max) or { panic("Couldn't obtain f64") }
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assert value >= 0.0
assert value < max
}
}
}
fn test_sys_rng_f32_in_range() {
min := f32(-24.0)
max := f32(125.0)
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.f32_in_range(min, max) or { panic("Couldn't obtain f32 in range") }
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assert value >= min
assert value < max
}
}
}
fn test_sys_rng_f64_in_range() {
min := -548.7
max := 5015.2
for seed in seeds {
seed_data := [seed]
mut rng := &rand.PRNG(&sys.SysRNG{})
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rng.seed(seed_data)
for _ in 0 .. range_limit {
value := rng.f64_in_range(min, max) or { panic("Couldn't obtain f64 in range") }
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assert value >= min
assert value < max
}
}
}