File size: 3,588 Bytes
4bcc2be | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 | // Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package rand_test
import (
"bytes"
"crypto/rand"
"fmt"
"io"
"math/big"
mathrand "math/rand"
"testing"
"time"
)
// https://golang.org/issue/6849.
func TestPrimeSmall(t *testing.T) {
for n := 2; n < 10; n++ {
p, err := rand.Prime(rand.Reader, n)
if err != nil {
t.Fatalf("Can't generate %d-bit prime: %v", n, err)
}
if p.BitLen() != n {
t.Fatalf("%v is not %d-bit", p, n)
}
if !p.ProbablyPrime(32) {
t.Fatalf("%v is not prime", p)
}
}
}
// Test that passing bits < 2 causes Prime to return nil, error
func TestPrimeBitsLt2(t *testing.T) {
if p, err := rand.Prime(rand.Reader, 1); p != nil || err == nil {
t.Errorf("Prime should return nil, error when called with bits < 2")
}
}
func TestPrimeNondeterministic(t *testing.T) {
r := mathrand.New(mathrand.NewSource(42))
p0, err := rand.Prime(r, 32)
if err != nil {
t.Fatal(err)
}
for i := 0; i < 128; i++ {
r.Seed(42)
p, err := rand.Prime(r, 32)
if err != nil {
t.Fatal(err)
}
if p.Cmp(p0) != 0 {
return
}
}
t.Error("Prime always generated the same prime given the same input")
}
func TestInt(t *testing.T) {
// start at 128 so the case of (max.BitLen() % 8) == 0 is covered
for n := 128; n < 140; n++ {
b := new(big.Int).SetInt64(int64(n))
if i, err := rand.Int(rand.Reader, b); err != nil {
t.Fatalf("Can't generate random value: %v, %v", i, err)
}
}
}
type countingReader struct {
r io.Reader
n int
}
func (r *countingReader) Read(p []byte) (n int, err error) {
n, err = r.r.Read(p)
r.n += n
return n, err
}
// Test that Int reads only the necessary number of bytes from the reader for
// max at each bit length
func TestIntReads(t *testing.T) {
for i := 0; i < 32; i++ {
max := int64(1 << uint64(i))
t.Run(fmt.Sprintf("max=%d", max), func(t *testing.T) {
reader := &countingReader{r: rand.Reader}
_, err := rand.Int(reader, big.NewInt(max))
if err != nil {
t.Fatalf("Can't generate random value: %d, %v", max, err)
}
expected := (i + 7) / 8
if reader.n != expected {
t.Errorf("Int(reader, %d) should read %d bytes, but it read: %d", max, expected, reader.n)
}
})
}
}
// Test that Int does not mask out valid return values
func TestIntMask(t *testing.T) {
for max := 1; max <= 256; max++ {
t.Run(fmt.Sprintf("max=%d", max), func(t *testing.T) {
for i := 0; i < max; i++ {
if testing.Short() && i == 0 {
i = max - 1
}
var b bytes.Buffer
b.WriteByte(byte(i))
n, err := rand.Int(&b, big.NewInt(int64(max)))
if err != nil {
t.Fatalf("Can't generate random value: %d, %v", max, err)
}
if n.Int64() != int64(i) {
t.Errorf("Int(reader, %d) should have returned value of %d, but it returned: %v", max, i, n)
}
}
})
}
}
func testIntPanics(t *testing.T, b *big.Int) {
defer func() {
if err := recover(); err == nil {
t.Errorf("Int should panic when called with max <= 0: %v", b)
}
}()
rand.Int(rand.Reader, b)
}
// Test that passing a new big.Int as max causes Int to panic
func TestIntEmptyMaxPanics(t *testing.T) {
b := new(big.Int)
testIntPanics(t, b)
}
// Test that passing a negative value as max causes Int to panic
func TestIntNegativeMaxPanics(t *testing.T) {
b := new(big.Int).SetInt64(int64(-1))
testIntPanics(t, b)
}
func BenchmarkPrime(b *testing.B) {
r := mathrand.New(mathrand.NewSource(time.Now().UnixNano()))
for i := 0; i < b.N; i++ {
rand.Prime(r, 1024)
}
}
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