131 lines
3.1 KiB
Go
131 lines
3.1 KiB
Go
// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package rand_test
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import (
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"bytes"
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"crypto/rand"
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"fmt"
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"io"
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"math/big"
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mathrand "math/rand"
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"testing"
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"time"
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)
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// https://golang.org/issue/6849.
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func TestPrimeSmall(t *testing.T) {
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for n := 2; n < 10; n++ {
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p, err := rand.Prime(rand.Reader, n)
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if err != nil {
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t.Fatalf("Can't generate %d-bit prime: %v", n, err)
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}
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if p.BitLen() != n {
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t.Fatalf("%v is not %d-bit", p, n)
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}
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if !p.ProbablyPrime(32) {
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t.Fatalf("%v is not prime", p)
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}
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}
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}
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// Test that passing bits < 2 causes Prime to return nil, error
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func TestPrimeBitsLt2(t *testing.T) {
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if p, err := rand.Prime(rand.Reader, 1); p != nil || err == nil {
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t.Errorf("Prime should return nil, error when called with bits < 2")
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}
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}
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func TestInt(t *testing.T) {
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// start at 128 so the case of (max.BitLen() % 8) == 0 is covered
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for n := 128; n < 140; n++ {
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b := new(big.Int).SetInt64(int64(n))
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if i, err := rand.Int(rand.Reader, b); err != nil {
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t.Fatalf("Can't generate random value: %v, %v", i, err)
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}
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}
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}
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type countingReader struct {
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r io.Reader
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n int
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}
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func (r *countingReader) Read(p []byte) (n int, err error) {
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n, err = r.r.Read(p)
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r.n += n
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return n, err
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}
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// Test that Int reads only the necessary number of bytes from the reader for
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// max at each bit length
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func TestIntReads(t *testing.T) {
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for i := 0; i < 32; i++ {
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max := int64(1 << uint64(i))
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t.Run(fmt.Sprintf("max=%d", max), func(t *testing.T) {
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reader := &countingReader{r: rand.Reader}
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_, err := rand.Int(reader, big.NewInt(max))
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if err != nil {
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t.Fatalf("Can't generate random value: %d, %v", max, err)
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}
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expected := (i + 7) / 8
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if reader.n != expected {
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t.Errorf("Int(reader, %d) should read %d bytes, but it read: %d", max, expected, reader.n)
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}
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})
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}
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}
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// Test that Int does not mask out valid return values
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func TestIntMask(t *testing.T) {
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for max := 1; max <= 256; max++ {
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t.Run(fmt.Sprintf("max=%d", max), func(t *testing.T) {
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for i := 0; i < max; i++ {
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if testing.Short() && i == 0 {
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i = max - 1
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}
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var b bytes.Buffer
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b.WriteByte(byte(i))
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n, err := rand.Int(&b, big.NewInt(int64(max)))
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if err != nil {
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t.Fatalf("Can't generate random value: %d, %v", max, err)
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}
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if n.Int64() != int64(i) {
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t.Errorf("Int(reader, %d) should have returned value of %d, but it returned: %v", max, i, n)
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}
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}
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})
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}
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}
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func testIntPanics(t *testing.T, b *big.Int) {
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defer func() {
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if err := recover(); err == nil {
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t.Errorf("Int should panic when called with max <= 0: %v", b)
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}
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}()
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rand.Int(rand.Reader, b)
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}
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// Test that passing a new big.Int as max causes Int to panic
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func TestIntEmptyMaxPanics(t *testing.T) {
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b := new(big.Int)
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testIntPanics(t, b)
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}
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// Test that passing a negative value as max causes Int to panic
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func TestIntNegativeMaxPanics(t *testing.T) {
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b := new(big.Int).SetInt64(int64(-1))
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testIntPanics(t, b)
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}
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func BenchmarkPrime(b *testing.B) {
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r := mathrand.New(mathrand.NewSource(time.Now().UnixNano()))
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for i := 0; i < b.N; i++ {
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rand.Prime(r, 1024)
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}
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}
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