go buffer_test 源码
golang buffer_test 代码
文件路径：/src/bytes/buffer_test.go
// Copyright 2009 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 bytes_test
import (
. "bytes"
"fmt"
"io"
"math/rand"
"testing"
"unicode/utf8"
)
const N = 10000 // make this bigger for a larger (and slower) test
var testString string // test data for write tests
var testBytes []byte // test data; same as testString but as a slice.
type negativeReader struct{}
func (r *negativeReader) Read([]byte) (int, error) { return -1, nil }
func init() {
testBytes = make([]byte, N)
for i := 0; i < N; i++ {
testBytes[i] = 'a' + byte(i%26)
}
testString = string(testBytes)
}
// Verify that contents of buf match the string s.
func check(t *testing.T, testname string, buf *Buffer, s string) {
bytes := buf.Bytes()
str := buf.String()
if buf.Len() != len(bytes) {
t.Errorf("%s: buf.Len() == %d, len(buf.Bytes()) == %d", testname, buf.Len(), len(bytes))
}
if buf.Len() != len(str) {
t.Errorf("%s: buf.Len() == %d, len(buf.String()) == %d", testname, buf.Len(), len(str))
}
if buf.Len() != len(s) {
t.Errorf("%s: buf.Len() == %d, len(s) == %d", testname, buf.Len(), len(s))
}
if string(bytes) != s {
t.Errorf("%s: string(buf.Bytes()) == %q, s == %q", testname, string(bytes), s)
}
}
// Fill buf through n writes of string fus.
// The initial contents of buf corresponds to the string s;
// the result is the final contents of buf returned as a string.
func fillString(t *testing.T, testname string, buf *Buffer, s string, n int, fus string) string {
check(t, testname+" (fill 1)", buf, s)
for ; n > 0; n-- {
m, err := buf.WriteString(fus)
if m != len(fus) {
t.Errorf(testname+" (fill 2): m == %d, expected %d", m, len(fus))
}
if err != nil {
t.Errorf(testname+" (fill 3): err should always be nil, found err == %s", err)
}
s += fus
check(t, testname+" (fill 4)", buf, s)
}
return s
}
// Fill buf through n writes of byte slice fub.
// The initial contents of buf corresponds to the string s;
// the result is the final contents of buf returned as a string.
func fillBytes(t *testing.T, testname string, buf *Buffer, s string, n int, fub []byte) string {
check(t, testname+" (fill 1)", buf, s)
for ; n > 0; n-- {
m, err := buf.Write(fub)
if m != len(fub) {
t.Errorf(testname+" (fill 2): m == %d, expected %d", m, len(fub))
}
if err != nil {
t.Errorf(testname+" (fill 3): err should always be nil, found err == %s", err)
}
s += string(fub)
check(t, testname+" (fill 4)", buf, s)
}
return s
}
func TestNewBuffer(t *testing.T) {
buf := NewBuffer(testBytes)
check(t, "NewBuffer", buf, testString)
}
func TestNewBufferString(t *testing.T) {
buf := NewBufferString(testString)
check(t, "NewBufferString", buf, testString)
}
// Empty buf through repeated reads into fub.
// The initial contents of buf corresponds to the string s.
func empty(t *testing.T, testname string, buf *Buffer, s string, fub []byte) {
check(t, testname+" (empty 1)", buf, s)
for {
n, err := buf.Read(fub)
if n == 0 {
break
}
if err != nil {
t.Errorf(testname+" (empty 2): err should always be nil, found err == %s", err)
}
s = s[n:]
check(t, testname+" (empty 3)", buf, s)
}
check(t, testname+" (empty 4)", buf, "")
}
func TestBasicOperations(t *testing.T) {
var buf Buffer
for i := 0; i < 5; i++ {
check(t, "TestBasicOperations (1)", &buf, "")
buf.Reset()
check(t, "TestBasicOperations (2)", &buf, "")
buf.Truncate(0)
check(t, "TestBasicOperations (3)", &buf, "")
n, err := buf.Write(testBytes[0:1])
if want := 1; err != nil || n != want {
t.Errorf("Write: got (%d, %v), want (%d, %v)", n, err, want, nil)
}
check(t, "TestBasicOperations (4)", &buf, "a")
buf.WriteByte(testString[1])
check(t, "TestBasicOperations (5)", &buf, "ab")
n, err = buf.Write(testBytes[2:26])
if want := 24; err != nil || n != want {
t.Errorf("Write: got (%d, %v), want (%d, %v)", n, err, want, nil)
}
check(t, "TestBasicOperations (6)", &buf, testString[0:26])
buf.Truncate(26)
check(t, "TestBasicOperations (7)", &buf, testString[0:26])
buf.Truncate(20)
check(t, "TestBasicOperations (8)", &buf, testString[0:20])
empty(t, "TestBasicOperations (9)", &buf, testString[0:20], make([]byte, 5))
empty(t, "TestBasicOperations (10)", &buf, "", make([]byte, 100))
buf.WriteByte(testString[1])
c, err := buf.ReadByte()
if want := testString[1]; err != nil || c != want {
t.Errorf("ReadByte: got (%q, %v), want (%q, %v)", c, err, want, nil)
}
c, err = buf.ReadByte()
if err != io.EOF {
t.Errorf("ReadByte: got (%q, %v), want (%q, %v)", c, err, byte(0), io.EOF)
}
}
}
func TestLargeStringWrites(t *testing.T) {
var buf Buffer
limit := 30
if testing.Short() {
limit = 9
}
for i := 3; i < limit; i += 3 {
s := fillString(t, "TestLargeWrites (1)", &buf, "", 5, testString)
empty(t, "TestLargeStringWrites (2)", &buf, s, make([]byte, len(testString)/i))
}
check(t, "TestLargeStringWrites (3)", &buf, "")
}
func TestLargeByteWrites(t *testing.T) {
var buf Buffer
limit := 30
if testing.Short() {
limit = 9
}
for i := 3; i < limit; i += 3 {
s := fillBytes(t, "TestLargeWrites (1)", &buf, "", 5, testBytes)
empty(t, "TestLargeByteWrites (2)", &buf, s, make([]byte, len(testString)/i))
}
check(t, "TestLargeByteWrites (3)", &buf, "")
}
func TestLargeStringReads(t *testing.T) {
var buf Buffer
for i := 3; i < 30; i += 3 {
s := fillString(t, "TestLargeReads (1)", &buf, "", 5, testString[0:len(testString)/i])
empty(t, "TestLargeReads (2)", &buf, s, make([]byte, len(testString)))
}
check(t, "TestLargeStringReads (3)", &buf, "")
}
func TestLargeByteReads(t *testing.T) {
var buf Buffer
for i := 3; i < 30; i += 3 {
s := fillBytes(t, "TestLargeReads (1)", &buf, "", 5, testBytes[0:len(testBytes)/i])
empty(t, "TestLargeReads (2)", &buf, s, make([]byte, len(testString)))
}
check(t, "TestLargeByteReads (3)", &buf, "")
}
func TestMixedReadsAndWrites(t *testing.T) {
var buf Buffer
s := ""
for i := 0; i < 50; i++ {
wlen := rand.Intn(len(testString))
if i%2 == 0 {
s = fillString(t, "TestMixedReadsAndWrites (1)", &buf, s, 1, testString[0:wlen])
} else {
s = fillBytes(t, "TestMixedReadsAndWrites (1)", &buf, s, 1, testBytes[0:wlen])
}
rlen := rand.Intn(len(testString))
fub := make([]byte, rlen)
n, _ := buf.Read(fub)
s = s[n:]
}
empty(t, "TestMixedReadsAndWrites (2)", &buf, s, make([]byte, buf.Len()))
}
func TestCapWithPreallocatedSlice(t *testing.T) {
buf := NewBuffer(make([]byte, 10))
n := buf.Cap()
if n != 10 {
t.Errorf("expected 10, got %d", n)
}
}
func TestCapWithSliceAndWrittenData(t *testing.T) {
buf := NewBuffer(make([]byte, 0, 10))
buf.Write([]byte("test"))
n := buf.Cap()
if n != 10 {
t.Errorf("expected 10, got %d", n)
}
}
func TestNil(t *testing.T) {
var b *Buffer
if b.String() != "<nil>" {
t.Errorf("expected <nil>; got %q", b.String())
}
}
func TestReadFrom(t *testing.T) {
var buf Buffer
for i := 3; i < 30; i += 3 {
s := fillBytes(t, "TestReadFrom (1)", &buf, "", 5, testBytes[0:len(testBytes)/i])
var b Buffer
b.ReadFrom(&buf)
empty(t, "TestReadFrom (2)", &b, s, make([]byte, len(testString)))
}
}
type panicReader struct{ panic bool }
func (r panicReader) Read(p []byte) (int, error) {
if r.panic {
panic(nil)
}
return 0, io.EOF
}
// Make sure that an empty Buffer remains empty when
// it is "grown" before a Read that panics
func TestReadFromPanicReader(t *testing.T) {
// First verify non-panic behaviour
var buf Buffer
i, err := buf.ReadFrom(panicReader{})
if err != nil {
t.Fatal(err)
}
if i != 0 {
t.Fatalf("unexpected return from bytes.ReadFrom (1): got: %d, want %d", i, 0)
}
check(t, "TestReadFromPanicReader (1)", &buf, "")
// Confirm that when Reader panics, the empty buffer remains empty
var buf2 Buffer
defer func() {
recover()
check(t, "TestReadFromPanicReader (2)", &buf2, "")
}()
buf2.ReadFrom(panicReader{panic: true})
}
func TestReadFromNegativeReader(t *testing.T) {
var b Buffer
defer func() {
switch err := recover().(type) {
case nil:
t.Fatal("bytes.Buffer.ReadFrom didn't panic")
case error:
// this is the error string of errNegativeRead
wantError := "bytes.Buffer: reader returned negative count from Read"
if err.Error() != wantError {
t.Fatalf("recovered panic: got %v, want %v", err.Error(), wantError)
}
default:
t.Fatalf("unexpected panic value: %#v", err)
}
}()
b.ReadFrom(new(negativeReader))
}
func TestWriteTo(t *testing.T) {
var buf Buffer
for i := 3; i < 30; i += 3 {
s := fillBytes(t, "TestWriteTo (1)", &buf, "", 5, testBytes[0:len(testBytes)/i])
var b Buffer
buf.WriteTo(&b)
empty(t, "TestWriteTo (2)", &b, s, make([]byte, len(testString)))
}
}
func TestRuneIO(t *testing.T) {
const NRune = 1000
// Built a test slice while we write the data
b := make([]byte, utf8.UTFMax*NRune)
var buf Buffer
n := 0
for r := rune(0); r < NRune; r++ {
size := utf8.EncodeRune(b[n:], r)
nbytes, err := buf.WriteRune(r)
if err != nil {
t.Fatalf("WriteRune(%U) error: %s", r, err)
}
if nbytes != size {
t.Fatalf("WriteRune(%U) expected %d, got %d", r, size, nbytes)
}
n += size
}
b = b[0:n]
// Check the resulting bytes
if !Equal(buf.Bytes(), b) {
t.Fatalf("incorrect result from WriteRune: %q not %q", buf.Bytes(), b)
}
p := make([]byte, utf8.UTFMax)
// Read it back with ReadRune
for r := rune(0); r < NRune; r++ {
size := utf8.EncodeRune(p, r)
nr, nbytes, err := buf.ReadRune()
if nr != r || nbytes != size || err != nil {
t.Fatalf("ReadRune(%U) got %U,%d not %U,%d (err=%s)", r, nr, nbytes, r, size, err)
}
}
// Check that UnreadRune works
buf.Reset()
// check at EOF
if err := buf.UnreadRune(); err == nil {
t.Fatal("UnreadRune at EOF: got no error")
}
if _, _, err := buf.ReadRune(); err == nil {
t.Fatal("ReadRune at EOF: got no error")
}
if err := buf.UnreadRune(); err == nil {
t.Fatal("UnreadRune after ReadRune at EOF: got no error")
}
// check not at EOF
buf.Write(b)
for r := rune(0); r < NRune; r++ {
r1, size, _ := buf.ReadRune()
if err := buf.UnreadRune(); err != nil {
t.Fatalf("UnreadRune(%U) got error %q", r, err)
}
r2, nbytes, err := buf.ReadRune()
if r1 != r2 || r1 != r || nbytes != size || err != nil {
t.Fatalf("ReadRune(%U) after UnreadRune got %U,%d not %U,%d (err=%s)", r, r2, nbytes, r, size, err)
}
}
}
func TestWriteInvalidRune(t *testing.T) {
// Invalid runes, including negative ones, should be written as
// utf8.RuneError.
for _, r := range []rune{-1, utf8.MaxRune + 1} {
var buf Buffer
buf.WriteRune(r)
check(t, fmt.Sprintf("TestWriteInvalidRune (%d)", r), &buf, "\uFFFD")
}
}
func TestNext(t *testing.T) {
b := []byte{0, 1, 2, 3, 4}
tmp := make([]byte, 5)
for i := 0; i <= 5; i++ {
for j := i; j <= 5; j++ {
for k := 0; k <= 6; k++ {
// 0 <= i <= j <= 5; 0 <= k <= 6
// Check that if we start with a buffer
// of length j at offset i and ask for
// Next(k), we get the right bytes.
buf := NewBuffer(b[0:j])
n, _ := buf.Read(tmp[0:i])
if n != i {
t.Fatalf("Read %d returned %d", i, n)
}
bb := buf.Next(k)
want := k
if want > j-i {
want = j - i
}
if len(bb) != want {
t.Fatalf("in %d,%d: len(Next(%d)) == %d", i, j, k, len(bb))
}
for l, v := range bb {
if v != byte(l+i) {
t.Fatalf("in %d,%d: Next(%d)[%d] = %d, want %d", i, j, k, l, v, l+i)
}
}
}
}
}
}
var readBytesTests = []struct {
buffer string
delim byte
expected []string
err error
}{
{"", 0, []string{""}, io.EOF},
{"a\x00", 0, []string{"a\x00"}, nil},
{"abbbaaaba", 'b', []string{"ab", "b", "b", "aaab"}, nil},
{"hello\x01world", 1, []string{"hello\x01"}, nil},
{"foo\nbar", 0, []string{"foo\nbar"}, io.EOF},
{"alpha\nbeta\ngamma\n", '\n', []string{"alpha\n", "beta\n", "gamma\n"}, nil},
{"alpha\nbeta\ngamma", '\n', []string{"alpha\n", "beta\n", "gamma"}, io.EOF},
}
func TestReadBytes(t *testing.T) {
for _, test := range readBytesTests {
buf := NewBufferString(test.buffer)
var err error
for _, expected := range test.expected {
var bytes []byte
bytes, err = buf.ReadBytes(test.delim)
if string(bytes) != expected {
t.Errorf("expected %q, got %q", expected, bytes)
}
if err != nil {
break
}
}
if err != test.err {
t.Errorf("expected error %v, got %v", test.err, err)
}
}
}
func TestReadString(t *testing.T) {
for _, test := range readBytesTests {
buf := NewBufferString(test.buffer)
var err error
for _, expected := range test.expected {
var s string
s, err = buf.ReadString(test.delim)
if s != expected {
t.Errorf("expected %q, got %q", expected, s)
}
if err != nil {
break
}
}
if err != test.err {
t.Errorf("expected error %v, got %v", test.err, err)
}
}
}
func BenchmarkReadString(b *testing.B) {
const n = 32 << 10
data := make([]byte, n)
data[n-1] = 'x'
b.SetBytes(int64(n))
for i := 0; i < b.N; i++ {
buf := NewBuffer(data)
_, err := buf.ReadString('x')
if err != nil {
b.Fatal(err)
}
}
}
func TestGrow(t *testing.T) {
x := []byte{'x'}
y := []byte{'y'}
tmp := make([]byte, 72)
for _, growLen := range []int{0, 100, 1000, 10000, 100000} {
for _, startLen := range []int{0, 100, 1000, 10000, 100000} {
xBytes := Repeat(x, startLen)
buf := NewBuffer(xBytes)
// If we read, this affects buf.off, which is good to test.
readBytes, _ := buf.Read(tmp)
yBytes := Repeat(y, growLen)
allocs := testing.AllocsPerRun(100, func() {
buf.Grow(growLen)
buf.Write(yBytes)
})
// Check no allocation occurs in write, as long as we're single-threaded.
if allocs != 0 {
t.Errorf("allocation occurred during write")
}
// Check that buffer has correct data.
if !Equal(buf.Bytes()[0:startLen-readBytes], xBytes[readBytes:]) {
t.Errorf("bad initial data at %d %d", startLen, growLen)
}
if !Equal(buf.Bytes()[startLen-readBytes:startLen-readBytes+growLen], yBytes) {
t.Errorf("bad written data at %d %d", startLen, growLen)
}
}
}
}
func TestGrowOverflow(t *testing.T) {
defer func() {
if err := recover(); err != ErrTooLarge {
t.Errorf("after too-large Grow, recover() = %v; want %v", err, ErrTooLarge)
}
}()
buf := NewBuffer(make([]byte, 1))
const maxInt = int(^uint(0) >> 1)
buf.Grow(maxInt)
}
// Was a bug: used to give EOF reading empty slice at EOF.
func TestReadEmptyAtEOF(t *testing.T) {
b := new(Buffer)
slice := make([]byte, 0)
n, err := b.Read(slice)
if err != nil {
t.Errorf("read error: %v", err)
}
if n != 0 {
t.Errorf("wrong count; got %d want 0", n)
}
}
func TestUnreadByte(t *testing.T) {
b := new(Buffer)
// check at EOF
if err := b.UnreadByte(); err == nil {
t.Fatal("UnreadByte at EOF: got no error")
}
if _, err := b.ReadByte(); err == nil {
t.Fatal("ReadByte at EOF: got no error")
}
if err := b.UnreadByte(); err == nil {
t.Fatal("UnreadByte after ReadByte at EOF: got no error")
}
// check not at EOF
b.WriteString("abcdefghijklmnopqrstuvwxyz")
// after unsuccessful read
if n, err := b.Read(nil); n != 0 || err != nil {
t.Fatalf("Read(nil) = %d,%v; want 0,nil", n, err)
}
if err := b.UnreadByte(); err == nil {
t.Fatal("UnreadByte after Read(nil): got no error")
}
// after successful read
if _, err := b.ReadBytes('m'); err != nil {
t.Fatalf("ReadBytes: %v", err)
}
if err := b.UnreadByte(); err != nil {
t.Fatalf("UnreadByte: %v", err)
}
c, err := b.ReadByte()
if err != nil {
t.Fatalf("ReadByte: %v", err)
}
if c != 'm' {
t.Errorf("ReadByte = %q; want %q", c, 'm')
}
}
// Tests that we occasionally compact. Issue 5154.
func TestBufferGrowth(t *testing.T) {
var b Buffer
buf := make([]byte, 1024)
b.Write(buf[0:1])
var cap0 int
for i := 0; i < 5<<10; i++ {
b.Write(buf)
b.Read(buf)
if i == 0 {
cap0 = b.Cap()
}
}
cap1 := b.Cap()
// (*Buffer).grow allows for 2x capacity slop before sliding,
// so set our error threshold at 3x.
if cap1 > cap0*3 {
t.Errorf("buffer cap = %d; too big (grew from %d)", cap1, cap0)
}
}
func BenchmarkWriteByte(b *testing.B) {
const n = 4 << 10
b.SetBytes(n)
buf := NewBuffer(make([]byte, n))
for i := 0; i < b.N; i++ {
buf.Reset()
for i := 0; i < n; i++ {
buf.WriteByte('x')
}
}
}
func BenchmarkWriteRune(b *testing.B) {
const n = 4 << 10
const r = '☺'
b.SetBytes(int64(n * utf8.RuneLen(r)))
buf := NewBuffer(make([]byte, n*utf8.UTFMax))
for i := 0; i < b.N; i++ {
buf.Reset()
for i := 0; i < n; i++ {
buf.WriteRune(r)
}
}
}
// From Issue 5154.
func BenchmarkBufferNotEmptyWriteRead(b *testing.B) {
buf := make([]byte, 1024)
for i := 0; i < b.N; i++ {
var b Buffer
b.Write(buf[0:1])
for i := 0; i < 5<<10; i++ {
b.Write(buf)
b.Read(buf)
}
}
}
// Check that we don't compact too often. From Issue 5154.
func BenchmarkBufferFullSmallReads(b *testing.B) {
buf := make([]byte, 1024)
for i := 0; i < b.N; i++ {
var b Buffer
b.Write(buf)
for b.Len()+20 < b.Cap() {
b.Write(buf[:10])
}
for i := 0; i < 5<<10; i++ {
b.Read(buf[:1])
b.Write(buf[:1])
}
}
}
func BenchmarkBufferWriteBlock(b *testing.B) {
block := make([]byte, 1024)
for _, n := range []int{1 << 12, 1 << 16, 1 << 20} {
b.Run(fmt.Sprintf("N%d", n), func(b *testing.B) {
b.ReportAllocs()
for i := 0; i < b.N; i++ {
var bb Buffer
for bb.Len() < n {
bb.Write(block)
}
}
})
}
}
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