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// Copyright 2012 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"
"sync"
"testing"
)
func TestReader(t *testing.T) {
r := NewReader([]byte("0123456789"))
tests := []struct {
off int64
seek int
n int
want string
wantpos int64
readerr error
seekerr string
}{
{seek: io.SeekStart, off: 0, n: 20, want: "0123456789"},
{seek: io.SeekStart, off: 1, n: 1, want: "1"},
{seek: io.SeekCurrent, off: 1, wantpos: 3, n: 2, want: "34"},
{seek: io.SeekStart, off: -1, seekerr: "bytes.Reader.Seek: negative position"},
{seek: io.SeekStart, off: 1 << 33, wantpos: 1 << 33, readerr: io.EOF},
{seek: io.SeekCurrent, off: 1, wantpos: 1<<33 + 1, readerr: io.EOF},
{seek: io.SeekStart, n: 5, want: "01234"},
{seek: io.SeekCurrent, n: 5, want: "56789"},
{seek: io.SeekEnd, off: -1, n: 1, wantpos: 9, want: "9"},
}
for i, tt := range tests {
pos, err := r.Seek(tt.off, tt.seek)
if err == nil && tt.seekerr != "" {
t.Errorf("%d. want seek error %q", i, tt.seekerr)
continue
}
if err != nil && err.Error() != tt.seekerr {
t.Errorf("%d. seek error = %q; want %q", i, err.Error(), tt.seekerr)
continue
}
if tt.wantpos != 0 && tt.wantpos != pos {
t.Errorf("%d. pos = %d, want %d", i, pos, tt.wantpos)
}
buf := make([]byte, tt.n)
n, err := r.Read(buf)
if err != tt.readerr {
t.Errorf("%d. read = %v; want %v", i, err, tt.readerr)
continue
}
got := string(buf[:n])
if got != tt.want {
t.Errorf("%d. got %q; want %q", i, got, tt.want)
}
}
}
func TestReadAfterBigSeek(t *testing.T) {
r := NewReader([]byte("0123456789"))
if _, err := r.Seek(1<<31+5, io.SeekStart); err != nil {
t.Fatal(err)
}
if n, err := r.Read(make([]byte, 10)); n != 0 || err != io.EOF {
t.Errorf("Read = %d, %v; want 0, EOF", n, err)
}
}
func TestReaderAt(t *testing.T) {
r := NewReader([]byte("0123456789"))
tests := []struct {
off int64
n int
want string
wanterr any
}{
{0, 10, "0123456789", nil},
{1, 10, "123456789", io.EOF},
{1, 9, "123456789", nil},
{11, 10, "", io.EOF},
{0, 0, "", nil},
{-1, 0, "", "bytes.Reader.ReadAt: negative offset"},
}
for i, tt := range tests {
b := make([]byte, tt.n)
rn, err := r.ReadAt(b, tt.off)
got := string(b[:rn])
if got != tt.want {
t.Errorf("%d. got %q; want %q", i, got, tt.want)
}
if fmt.Sprintf("%v", err) != fmt.Sprintf("%v", tt.wanterr) {
t.Errorf("%d. got error = %v; want %v", i, err, tt.wanterr)
}
}
}
func TestReaderAtConcurrent(t *testing.T) {
// Test for the race detector, to verify ReadAt doesn't mutate
// any state.
r := NewReader([]byte("0123456789"))
var wg sync.WaitGroup
for i := 0; i < 5; i++ {
wg.Add(1)
go func(i int) {
defer wg.Done()
var buf [1]byte
r.ReadAt(buf[:], int64(i))
}(i)
}
wg.Wait()
}
func TestEmptyReaderConcurrent(t *testing.T) {
// Test for the race detector, to verify a Read that doesn't yield any bytes
// is okay to use from multiple goroutines. This was our historic behavior.
// See golang.org/issue/7856
r := NewReader([]byte{})
var wg sync.WaitGroup
for i := 0; i < 5; i++ {
wg.Add(2)
go func() {
defer wg.Done()
var buf [1]byte
r.Read(buf[:])
}()
go func() {
defer wg.Done()
r.Read(nil)
}()
}
wg.Wait()
}
func TestReaderWriteTo(t *testing.T) {
for i := 0; i < 30; i += 3 {
var l int
if i > 0 {
l = len(testString) / i
}
s := testString[:l]
r := NewReader(testBytes[:l])
var b Buffer
n, err := r.WriteTo(&b)
if expect := int64(len(s)); n != expect {
t.Errorf("got %v; want %v", n, expect)
}
if err != nil {
t.Errorf("for length %d: got error = %v; want nil", l, err)
}
if b.String() != s {
t.Errorf("got string %q; want %q", b.String(), s)
}
if r.Len() != 0 {
t.Errorf("reader contains %v bytes; want 0", r.Len())
}
}
}
func TestReaderLen(t *testing.T) {
const data = "hello world"
r := NewReader([]byte(data))
if got, want := r.Len(), 11; got != want {
t.Errorf("r.Len(): got %d, want %d", got, want)
}
if n, err := r.Read(make([]byte, 10)); err != nil || n != 10 {
t.Errorf("Read failed: read %d %v", n, err)
}
if got, want := r.Len(), 1; got != want {
t.Errorf("r.Len(): got %d, want %d", got, want)
}
if n, err := r.Read(make([]byte, 1)); err != nil || n != 1 {
t.Errorf("Read failed: read %d %v; want 1, nil", n, err)
}
if got, want := r.Len(), 0; got != want {
t.Errorf("r.Len(): got %d, want %d", got, want)
}
}
var UnreadRuneErrorTests = []struct {
name string
f func(*Reader)
}{
{"Read", func(r *Reader) { r.Read([]byte{0}) }},
{"ReadByte", func(r *Reader) { r.ReadByte() }},
{"UnreadRune", func(r *Reader) { r.UnreadRune() }},
{"Seek", func(r *Reader) { r.Seek(0, io.SeekCurrent) }},
{"WriteTo", func(r *Reader) { r.WriteTo(&Buffer{}) }},
}
func TestUnreadRuneError(t *testing.T) {
for _, tt := range UnreadRuneErrorTests {
reader := NewReader([]byte("0123456789"))
if _, _, err := reader.ReadRune(); err != nil {
// should not happen
t.Fatal(err)
}
tt.f(reader)
err := reader.UnreadRune()
if err == nil {
t.Errorf("Unreading after %s: expected error", tt.name)
}
}
}
func TestReaderDoubleUnreadRune(t *testing.T) {
buf := NewBuffer([]byte("groucho"))
if _, _, err := buf.ReadRune(); err != nil {
// should not happen
t.Fatal(err)
}
if err := buf.UnreadByte(); err != nil {
// should not happen
t.Fatal(err)
}
if err := buf.UnreadByte(); err == nil {
t.Fatal("UnreadByte: expected error, got nil")
}
}
// verify that copying from an empty reader always has the same results,
// regardless of the presence of a WriteTo method.
func TestReaderCopyNothing(t *testing.T) {
type nErr struct {
n int64
err error
}
type justReader struct {
io.Reader
}
type justWriter struct {
io.Writer
}
discard := justWriter{io.Discard} // hide ReadFrom
var with, withOut nErr
with.n, with.err = io.Copy(discard, NewReader(nil))
withOut.n, withOut.err = io.Copy(discard, justReader{NewReader(nil)})
if with != withOut {
t.Errorf("behavior differs: with = %#v; without: %#v", with, withOut)
}
}
// tests that Len is affected by reads, but Size is not.
func TestReaderLenSize(t *testing.T) {
r := NewReader([]byte("abc"))
io.CopyN(io.Discard, r, 1)
if r.Len() != 2 {
t.Errorf("Len = %d; want 2", r.Len())
}
if r.Size() != 3 {
t.Errorf("Size = %d; want 3", r.Size())
}
}
func TestReaderReset(t *testing.T) {
r := NewReader([]byte("世界"))
if _, _, err := r.ReadRune(); err != nil {
t.Errorf("ReadRune: unexpected error: %v", err)
}
const want = "abcdef"
r.Reset([]byte(want))
if err := r.UnreadRune(); err == nil {
t.Errorf("UnreadRune: expected error, got nil")
}
buf, err := io.ReadAll(r)
if err != nil {
t.Errorf("ReadAll: unexpected error: %v", err)
}
if got := string(buf); got != want {
t.Errorf("ReadAll: got %q, want %q", got, want)
}
}
func TestReaderZero(t *testing.T) {
if l := (&Reader{}).Len(); l != 0 {
t.Errorf("Len: got %d, want 0", l)
}
if n, err := (&Reader{}).Read(nil); n != 0 || err != io.EOF {
t.Errorf("Read: got %d, %v; want 0, io.EOF", n, err)
}
if n, err := (&Reader{}).ReadAt(nil, 11); n != 0 || err != io.EOF {
t.Errorf("ReadAt: got %d, %v; want 0, io.EOF", n, err)
}
if b, err := (&Reader{}).ReadByte(); b != 0 || err != io.EOF {
t.Errorf("ReadByte: got %d, %v; want 0, io.EOF", b, err)
}
if ch, size, err := (&Reader{}).ReadRune(); ch != 0 || size != 0 || err != io.EOF {
t.Errorf("ReadRune: got %d, %d, %v; want 0, 0, io.EOF", ch, size, err)
}
if offset, err := (&Reader{}).Seek(11, io.SeekStart); offset != 11 || err != nil {
t.Errorf("Seek: got %d, %v; want 11, nil", offset, err)
}
if s := (&Reader{}).Size(); s != 0 {
t.Errorf("Size: got %d, want 0", s)
}
if (&Reader{}).UnreadByte() == nil {
t.Errorf("UnreadByte: got nil, want error")
}
if (&Reader{}).UnreadRune() == nil {
t.Errorf("UnreadRune: got nil, want error")
}
if n, err := (&Reader{}).WriteTo(io.Discard); n != 0 || err != nil {
t.Errorf("WriteTo: got %d, %v; want 0, nil", n, err)
}
}