goutils/rand/rand_test.go

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package rand
import (
"fmt"
mrand "math/rand"
"testing"
)
func TestCryptoUint64(t *testing.T) {
n1, err := CryptoUint64()
if err != nil {
t.Fatal(err)
}
n2, err := CryptoUint64()
if err != nil {
t.Fatal(err)
}
// This has such a low chance of occurring that it's likely to be
// indicative of a bad CSPRNG.
if n1 == n2 {
t.Fatalf("repeated random uint64s: %d", n1)
}
}
func TestIntn(t *testing.T) {
expected := []int{3081, 4887, 4847, 1059, 3081}
mrand.Seed(1)
for i := 0; i < 5; i++ {
n := Intn2(1000, 5000)
if n != expected[i] {
fmt.Printf("invalid sequence at %d: expected %d, have %d", i, expected[i], n)
}
}
}
func TestSeed(t *testing.T) {
seed1, err := Seed()
if err != nil {
t.Fatal(err)
}
var seed2 uint64
n1 := Int()
tries := 0
for {
seed2, err = Seed()
if err != nil {
t.Fatal(err)
}
if seed1 != seed2 {
break
}
tries++
if tries > 3 {
t.Fatal("can't generate two unique seeds")
}
}
n2 := Int()
// Again, this not impossible, merely statistically improbably and a
// potential canary for RNG issues.
if n1 == n2 {
t.Fatalf("repeated integers fresh from two unique seeds: %d/%d -> %d",
seed1, seed2, n1)
}
}