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// 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 io_test
import (
"bytes"
"errors"
"fmt"
. "io"
"strings"
"testing"
)
// An version of bytes.Buffer without ReadFrom and WriteTo
type Buffer struct {
bytes.Buffer
ReaderFrom // conflicts with and hides bytes.Buffer's ReaderFrom.
WriterTo // conflicts with and hides bytes.Buffer's WriterTo.
}
// Simple tests, primarily to verify the ReadFrom and WriteTo callouts inside Copy and CopyN.
func TestCopy(t *testing.T) {
rb := new(Buffer)
wb := new(Buffer)
rb.WriteString("hello, world.")
Copy(wb, rb)
if wb.String() != "hello, world." {
t.Errorf("Copy did not work properly")
}
}
func TestCopyReadFrom(t *testing.T) {
rb := new(Buffer)
wb := new(bytes.Buffer) // implements ReadFrom.
rb.WriteString("hello, world.")
Copy(wb, rb)
if wb.String() != "hello, world." {
t.Errorf("Copy did not work properly")
}
}
func TestCopyWriteTo(t *testing.T) {
rb := new(bytes.Buffer) // implements WriteTo.
wb := new(Buffer)
rb.WriteString("hello, world.")
Copy(wb, rb)
if wb.String() != "hello, world." {
t.Errorf("Copy did not work properly")
}
}
// Version of bytes.Buffer that checks whether WriteTo was called or not
type writeToChecker struct {
bytes.Buffer
writeToCalled bool
}
func (wt *writeToChecker) WriteTo(w Writer) (int64, error) {
wt.writeToCalled = true
return wt.Buffer.WriteTo(w)
}
// It's preferable to choose WriterTo over ReaderFrom, since a WriterTo can issue one large write,
// while the ReaderFrom must read until EOF, potentially allocating when running out of buffer.
// Make sure that we choose WriterTo when both are implemented.
func TestCopyPriority(t *testing.T) {
rb := new(writeToChecker)
wb := new(bytes.Buffer)
rb.WriteString("hello, world.")
Copy(wb, rb)
if wb.String() != "hello, world." {
t.Errorf("Copy did not work properly")
} else if !rb.writeToCalled {
t.Errorf("WriteTo was not prioritized over ReadFrom")
}
}
func TestCopyN(t *testing.T) {
rb := new(Buffer)
wb := new(Buffer)
rb.WriteString("hello, world.")
CopyN(wb, rb, 5)
if wb.String() != "hello" {
t.Errorf("CopyN did not work properly")
}
}
func TestCopyNReadFrom(t *testing.T) {
rb := new(Buffer)
wb := new(bytes.Buffer) // implements ReadFrom.
rb.WriteString("hello")
CopyN(wb, rb, 5)
if wb.String() != "hello" {
t.Errorf("CopyN did not work properly")
}
}
func TestCopyNWriteTo(t *testing.T) {
rb := new(bytes.Buffer) // implements WriteTo.
wb := new(Buffer)
rb.WriteString("hello, world.")
CopyN(wb, rb, 5)
if wb.String() != "hello" {
t.Errorf("CopyN did not work properly")
}
}
type noReadFrom struct {
w Writer
}
func (w *noReadFrom) Write(p []byte) (n int, err error) {
return w.w.Write(p)
}
type wantedAndErrReader struct{}
func (wantedAndErrReader) Read(p []byte) (int, error) {
return len(p), errors.New("wantedAndErrReader error")
}
func TestCopyNEOF(t *testing.T) {
// Test that EOF behavior is the same regardless of whether
// argument to CopyN has ReadFrom.
b := new(bytes.Buffer)
n, err := CopyN(&noReadFrom{b}, strings.NewReader("foo"), 3)
if n != 3 || err != nil {
t.Errorf("CopyN(noReadFrom, foo, 3) = %d, %v; want 3, nil", n, err)
}
n, err = CopyN(&noReadFrom{b}, strings.NewReader("foo"), 4)
if n != 3 || err != EOF {
t.Errorf("CopyN(noReadFrom, foo, 4) = %d, %v; want 3, EOF", n, err)
}
n, err = CopyN(b, strings.NewReader("foo"), 3) // b has read from
if n != 3 || err != nil {
t.Errorf("CopyN(bytes.Buffer, foo, 3) = %d, %v; want 3, nil", n, err)
}
n, err = CopyN(b, strings.NewReader("foo"), 4) // b has read from
if n != 3 || err != EOF {
t.Errorf("CopyN(bytes.Buffer, foo, 4) = %d, %v; want 3, EOF", n, err)
}
n, err = CopyN(b, wantedAndErrReader{}, 5)
if n != 5 || err != nil {
t.Errorf("CopyN(bytes.Buffer, wantedAndErrReader, 5) = %d, %v; want 5, nil", n, err)
}
n, err = CopyN(&noReadFrom{b}, wantedAndErrReader{}, 5)
if n != 5 || err != nil {
t.Errorf("CopyN(noReadFrom, wantedAndErrReader, 5) = %d, %v; want 5, nil", n, err)
}
}
func TestReadAtLeast(t *testing.T) {
var rb bytes.Buffer
testReadAtLeast(t, &rb)
}
// A version of bytes.Buffer that returns n > 0, err on Read
// when the input is exhausted.
type dataAndErrorBuffer struct {
err error
bytes.Buffer
}
func (r *dataAndErrorBuffer) Read(p []byte) (n int, err error) {
n, err = r.Buffer.Read(p)
if n > 0 && r.Buffer.Len() == 0 && err == nil {
err = r.err
}
return
}
func TestReadAtLeastWithDataAndEOF(t *testing.T) {
var rb dataAndErrorBuffer
rb.err = EOF
testReadAtLeast(t, &rb)
}
func TestReadAtLeastWithDataAndError(t *testing.T) {
var rb dataAndErrorBuffer
rb.err = fmt.Errorf("fake error")
testReadAtLeast(t, &rb)
}
func testReadAtLeast(t *testing.T, rb ReadWriter) {
rb.Write([]byte("0123"))
buf := make([]byte, 2)
n, err := ReadAtLeast(rb, buf, 2)
if err != nil {
t.Error(err)
}
n, err = ReadAtLeast(rb, buf, 4)
if err != ErrShortBuffer {
t.Errorf("expected ErrShortBuffer got %v", err)
}
if n != 0 {
t.Errorf("expected to have read 0 bytes, got %v", n)
}
n, err = ReadAtLeast(rb, buf, 1)
if err != nil {
t.Error(err)
}
if n != 2 {
t.Errorf("expected to have read 2 bytes, got %v", n)
}
n, err = ReadAtLeast(rb, buf, 2)
if err != EOF {
t.Errorf("expected EOF, got %v", err)
}
if n != 0 {
t.Errorf("expected to have read 0 bytes, got %v", n)
}
rb.Write([]byte("4"))
n, err = ReadAtLeast(rb, buf, 2)
want := ErrUnexpectedEOF
if rb, ok := rb.(*dataAndErrorBuffer); ok && rb.err != EOF {
want = rb.err
}
if err != want {
t.Errorf("expected %v, got %v", want, err)
}
if n != 1 {
t.Errorf("expected to have read 1 bytes, got %v", n)
}
}
func TestTeeReader(t *testing.T) {
src := []byte("hello, world")
dst := make([]byte, len(src))
rb := bytes.NewBuffer(src)
wb := new(bytes.Buffer)
r := TeeReader(rb, wb)
if n, err := ReadFull(r, dst); err != nil || n != len(src) {
t.Fatalf("ReadFull(r, dst) = %d, %v; want %d, nil", n, err, len(src))
}
if !bytes.Equal(dst, src) {
t.Errorf("bytes read = %q want %q", dst, src)
}
if !bytes.Equal(wb.Bytes(), src) {
t.Errorf("bytes written = %q want %q", wb.Bytes(), src)
}
if n, err := r.Read(dst); n != 0 || err != EOF {
t.Errorf("r.Read at EOF = %d, %v want 0, EOF", n, err)
}
rb = bytes.NewBuffer(src)
pr, pw := Pipe()
pr.Close()
r = TeeReader(rb, pw)
if n, err := ReadFull(r, dst); n != 0 || err != ErrClosedPipe {
t.Errorf("closed tee: ReadFull(r, dst) = %d, %v; want 0, EPIPE", n, err)
}
}
func TestSectionReader_ReadAt(t *testing.T) {
dat := "a long sample data, 1234567890"
tests := []struct {
data string
off int
n int
bufLen int
at int
exp string
err error
}{
{data: "", off: 0, n: 10, bufLen: 2, at: 0, exp: "", err: EOF},
{data: dat, off: 0, n: len(dat), bufLen: 0, at: 0, exp: "", err: nil},
{data: dat, off: len(dat), n: 1, bufLen: 1, at: 0, exp: "", err: EOF},
{data: dat, off: 0, n: len(dat) + 2, bufLen: len(dat), at: 0, exp: dat, err: nil},
{data: dat, off: 0, n: len(dat), bufLen: len(dat) / 2, at: 0, exp: dat[:len(dat)/2], err: nil},
{data: dat, off: 0, n: len(dat), bufLen: len(dat), at: 0, exp: dat, err: nil},
{data: dat, off: 0, n: len(dat), bufLen: len(dat) / 2, at: 2, exp: dat[2 : 2+len(dat)/2], err: nil},
{data: dat, off: 3, n: len(dat), bufLen: len(dat) / 2, at: 2, exp: dat[5 : 5+len(dat)/2], err: nil},
{data: dat, off: 3, n: len(dat) / 2, bufLen: len(dat)/2 - 2, at: 2, exp: dat[5 : 5+len(dat)/2-2], err: nil},
{data: dat, off: 3, n: len(dat) / 2, bufLen: len(dat)/2 + 2, at: 2, exp: dat[5 : 5+len(dat)/2-2], err: EOF},
}
for i, tt := range tests {
r := strings.NewReader(tt.data)
s := NewSectionReader(r, int64(tt.off), int64(tt.n))
buf := make([]byte, tt.bufLen)
if n, err := s.ReadAt(buf, int64(tt.at)); n != len(tt.exp) || string(buf[:n]) != tt.exp || err != tt.err {
t.Fatalf("%d: ReadAt(%d) = %q, %v; expected %q, %v", i, tt.at, buf[:n], err, tt.exp, tt.err)
}
}
}
func TestSectionReader_Seek(t *testing.T) {
// Verifies that NewSectionReader's Seeker behaves like bytes.NewReader (which is like strings.NewReader)
br := bytes.NewReader([]byte("foo"))
sr := NewSectionReader(br, 0, int64(len("foo")))
for whence := 0; whence <= 2; whence++ {
for offset := int64(-3); offset <= 4; offset++ {
brOff, brErr := br.Seek(offset, whence)
srOff, srErr := sr.Seek(offset, whence)
if (brErr != nil) != (srErr != nil) || brOff != srOff {
t.Errorf("For whence %d, offset %d: bytes.Reader.Seek = (%v, %v) != SectionReader.Seek = (%v, %v)",
whence, offset, brOff, brErr, srErr, srOff)
}
}
}
// And verify we can just seek past the end and get an EOF
got, err := sr.Seek(100, 0)
if err != nil || got != 100 {
t.Errorf("Seek = %v, %v; want 100, nil", got, err)
}
n, err := sr.Read(make([]byte, 10))
if n != 0 || err != EOF {
t.Errorf("Read = %v, %v; want 0, EOF", n, err)
}
}
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