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// Copyright 2019 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 maphash
import (
"bytes"
"fmt"
"hash"
"testing"
)
func TestUnseededHash(t *testing.T) {
m := map[uint64]struct{}{}
for i := 0; i < 1000; i++ {
h := new(Hash)
m[h.Sum64()] = struct{}{}
}
if len(m) < 900 {
t.Errorf("empty hash not sufficiently random: got %d, want 1000", len(m))
}
}
func TestSeededHash(t *testing.T) {
s := MakeSeed()
m := map[uint64]struct{}{}
for i := 0; i < 1000; i++ {
h := new(Hash)
h.SetSeed(s)
m[h.Sum64()] = struct{}{}
}
if len(m) != 1 {
t.Errorf("seeded hash is random: got %d, want 1", len(m))
}
}
func TestHashGrouping(t *testing.T) {
b := bytes.Repeat([]byte("foo"), 100)
hh := make([]*Hash, 7)
for i := range hh {
hh[i] = new(Hash)
}
for _, h := range hh[1:] {
h.SetSeed(hh[0].Seed())
}
hh[0].Write(b)
hh[1].WriteString(string(b))
writeByte := func(h *Hash, b byte) {
err := h.WriteByte(b)
if err != nil {
t.Fatalf("WriteByte: %v", err)
}
}
writeSingleByte := func(h *Hash, b byte) {
_, err := h.Write([]byte{b})
if err != nil {
t.Fatalf("Write single byte: %v", err)
}
}
writeStringSingleByte := func(h *Hash, b byte) {
_, err := h.WriteString(string([]byte{b}))
if err != nil {
t.Fatalf("WriteString single byte: %v", err)
}
}
for i, x := range b {
writeByte(hh[2], x)
writeSingleByte(hh[3], x)
if i == 0 {
writeByte(hh[4], x)
} else {
writeSingleByte(hh[4], x)
}
writeStringSingleByte(hh[5], x)
if i == 0 {
writeByte(hh[6], x)
} else {
writeStringSingleByte(hh[6], x)
}
}
sum := hh[0].Sum64()
for i, h := range hh {
if sum != h.Sum64() {
t.Errorf("hash %d not identical to a single Write", i)
}
}
if sum1 := Bytes(hh[0].Seed(), b); sum1 != hh[0].Sum64() {
t.Errorf("hash using Bytes not identical to a single Write")
}
if sum1 := String(hh[0].Seed(), string(b)); sum1 != hh[0].Sum64() {
t.Errorf("hash using String not identical to a single Write")
}
}
func TestHashBytesVsString(t *testing.T) {
s := "foo"
b := []byte(s)
h1 := new(Hash)
h2 := new(Hash)
h2.SetSeed(h1.Seed())
n1, err1 := h1.WriteString(s)
if n1 != len(s) || err1 != nil {
t.Fatalf("WriteString(s) = %d, %v, want %d, nil", n1, err1, len(s))
}
n2, err2 := h2.Write(b)
if n2 != len(b) || err2 != nil {
t.Fatalf("Write(b) = %d, %v, want %d, nil", n2, err2, len(b))
}
if h1.Sum64() != h2.Sum64() {
t.Errorf("hash of string and bytes not identical")
}
}
func TestHashHighBytes(t *testing.T) {
// See issue 34925.
const N = 10
m := map[uint64]struct{}{}
for i := 0; i < N; i++ {
h := new(Hash)
h.WriteString("foo")
m[h.Sum64()>>32] = struct{}{}
}
if len(m) < N/2 {
t.Errorf("from %d seeds, wanted at least %d different hashes; got %d", N, N/2, len(m))
}
}
func TestRepeat(t *testing.T) {
h1 := new(Hash)
h1.WriteString("testing")
sum1 := h1.Sum64()
h1.Reset()
h1.WriteString("testing")
sum2 := h1.Sum64()
if sum1 != sum2 {
t.Errorf("different sum after reseting: %#x != %#x", sum1, sum2)
}
h2 := new(Hash)
h2.SetSeed(h1.Seed())
h2.WriteString("testing")
sum3 := h2.Sum64()
if sum1 != sum3 {
t.Errorf("different sum on the same seed: %#x != %#x", sum1, sum3)
}
}
func TestSeedFromSum64(t *testing.T) {
h1 := new(Hash)
h1.WriteString("foo")
x := h1.Sum64() // seed generated here
h2 := new(Hash)
h2.SetSeed(h1.Seed())
h2.WriteString("foo")
y := h2.Sum64()
if x != y {
t.Errorf("hashes don't match: want %x, got %x", x, y)
}
}
func TestSeedFromSeed(t *testing.T) {
h1 := new(Hash)
h1.WriteString("foo")
_ = h1.Seed() // seed generated here
x := h1.Sum64()
h2 := new(Hash)
h2.SetSeed(h1.Seed())
h2.WriteString("foo")
y := h2.Sum64()
if x != y {
t.Errorf("hashes don't match: want %x, got %x", x, y)
}
}
func TestSeedFromFlush(t *testing.T) {
b := make([]byte, 65)
h1 := new(Hash)
h1.Write(b) // seed generated here
x := h1.Sum64()
h2 := new(Hash)
h2.SetSeed(h1.Seed())
h2.Write(b)
y := h2.Sum64()
if x != y {
t.Errorf("hashes don't match: want %x, got %x", x, y)
}
}
func TestSeedFromReset(t *testing.T) {
h1 := new(Hash)
h1.WriteString("foo")
h1.Reset() // seed generated here
h1.WriteString("foo")
x := h1.Sum64()
h2 := new(Hash)
h2.SetSeed(h1.Seed())
h2.WriteString("foo")
y := h2.Sum64()
if x != y {
t.Errorf("hashes don't match: want %x, got %x", x, y)
}
}
// Make sure a Hash implements the hash.Hash and hash.Hash64 interfaces.
var _ hash.Hash = &Hash{}
var _ hash.Hash64 = &Hash{}
func benchmarkSize(b *testing.B, size int) {
h := &Hash{}
buf := make([]byte, size)
s := string(buf)
b.Run("Write", func(b *testing.B) {
b.SetBytes(int64(size))
for i := 0; i < b.N; i++ {
h.Reset()
h.Write(buf)
h.Sum64()
}
})
b.Run("Bytes", func(b *testing.B) {
b.SetBytes(int64(size))
seed := h.Seed()
for i := 0; i < b.N; i++ {
Bytes(seed, buf)
}
})
b.Run("String", func(b *testing.B) {
b.SetBytes(int64(size))
seed := h.Seed()
for i := 0; i < b.N; i++ {
String(seed, s)
}
})
}
func BenchmarkHash(b *testing.B) {
sizes := []int{4, 8, 16, 32, 64, 256, 320, 1024, 4096, 16384}
for _, size := range sizes {
b.Run(fmt.Sprint("n=", size), func(b *testing.B) {
benchmarkSize(b, size)
})
}
}
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