libgo/go/io/io_test.go

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package io_test
   6
   7 import (
   8         "bytes"
   9         "errors"
  10         "fmt"
  11         . "io"
  12         "strings"
  13         "testing"
  14 )
  15
  16 // An version of bytes.Buffer without ReadFrom and WriteTo
  17 type Buffer struct {
  18         bytes.Buffer
  19         ReaderFrom // conflicts with and hides bytes.Buffer's ReaderFrom.
  20         WriterTo   // conflicts with and hides bytes.Buffer's WriterTo.
  21 }
  22
  23 // Simple tests, primarily to verify the ReadFrom and WriteTo callouts inside Copy and CopyN.
  24
  25 func TestCopy(t *testing.T) {
  26         rb := new(Buffer)
  27         wb := new(Buffer)
  28         rb.WriteString("hello, world.")
  29         Copy(wb, rb)
  30         if wb.String() != "hello, world." {
  31                 t.Errorf("Copy did not work properly")
  32         }
  33 }
  34
  35 func TestCopyReadFrom(t *testing.T) {
  36         rb := new(Buffer)
  37         wb := new(bytes.Buffer) // implements ReadFrom.
  38         rb.WriteString("hello, world.")
  39         Copy(wb, rb)
  40         if wb.String() != "hello, world." {
  41                 t.Errorf("Copy did not work properly")
  42         }
  43 }
  44
  45 func TestCopyWriteTo(t *testing.T) {
  46         rb := new(bytes.Buffer) // implements WriteTo.
  47         wb := new(Buffer)
  48         rb.WriteString("hello, world.")
  49         Copy(wb, rb)
  50         if wb.String() != "hello, world." {
  51                 t.Errorf("Copy did not work properly")
  52         }
  53 }
  54
  55 // Version of bytes.Buffer that checks whether WriteTo was called or not
  56 type writeToChecker struct {
  57         bytes.Buffer
  58         writeToCalled bool
  59 }
  60
  61 func (wt *writeToChecker) WriteTo(w Writer) (int64, error) {
  62         wt.writeToCalled = true
  63         return wt.Buffer.WriteTo(w)
  64 }
  65
  66 // It's preferable to choose WriterTo over ReaderFrom, since a WriterTo can issue one large write,
  67 // while the ReaderFrom must read until EOF, potentially allocating when running out of buffer.
  68 // Make sure that we choose WriterTo when both are implemented.
  69 func TestCopyPriority(t *testing.T) {
  70         rb := new(writeToChecker)
  71         wb := new(bytes.Buffer)
  72         rb.WriteString("hello, world.")
  73         Copy(wb, rb)
  74         if wb.String() != "hello, world." {
  75                 t.Errorf("Copy did not work properly")
  76         } else if !rb.writeToCalled {
  77                 t.Errorf("WriteTo was not prioritized over ReadFrom")
  78         }
  79 }
  80
  81 func TestCopyN(t *testing.T) {
  82         rb := new(Buffer)
  83         wb := new(Buffer)
  84         rb.WriteString("hello, world.")
  85         CopyN(wb, rb, 5)
  86         if wb.String() != "hello" {
  87                 t.Errorf("CopyN did not work properly")
  88         }
  89 }
  90
  91 func TestCopyNReadFrom(t *testing.T) {
  92         rb := new(Buffer)
  93         wb := new(bytes.Buffer) // implements ReadFrom.
  94         rb.WriteString("hello")
  95         CopyN(wb, rb, 5)
  96         if wb.String() != "hello" {
  97                 t.Errorf("CopyN did not work properly")
  98         }
  99 }
 100
 101 func TestCopyNWriteTo(t *testing.T) {
 102         rb := new(bytes.Buffer) // implements WriteTo.
 103         wb := new(Buffer)
 104         rb.WriteString("hello, world.")
 105         CopyN(wb, rb, 5)
 106         if wb.String() != "hello" {
 107                 t.Errorf("CopyN did not work properly")
 108         }
 109 }
 110
 111 type noReadFrom struct {
 112         w Writer
 113 }
 114
 115 func (w *noReadFrom) Write(p []byte) (n int, err error) {
 116         return w.w.Write(p)
 117 }
 118
 119 type wantedAndErrReader struct{}
 120
 121 func (wantedAndErrReader) Read(p []byte) (int, error) {
 122         return len(p), errors.New("wantedAndErrReader error")
 123 }
 124
 125 func TestCopyNEOF(t *testing.T) {
 126         // Test that EOF behavior is the same regardless of whether
 127         // argument to CopyN has ReadFrom.
 128
 129         b := new(bytes.Buffer)
 130
 131         n, err := CopyN(&noReadFrom{b}, strings.NewReader("foo"), 3)
 132         if n != 3 || err != nil {
 133                 t.Errorf("CopyN(noReadFrom, foo, 3) = %d, %v; want 3, nil", n, err)
 134         }
 135
 136         n, err = CopyN(&noReadFrom{b}, strings.NewReader("foo"), 4)
 137         if n != 3 || err != EOF {
 138                 t.Errorf("CopyN(noReadFrom, foo, 4) = %d, %v; want 3, EOF", n, err)
 139         }
 140
 141         n, err = CopyN(b, strings.NewReader("foo"), 3) // b has read from
 142         if n != 3 || err != nil {
 143                 t.Errorf("CopyN(bytes.Buffer, foo, 3) = %d, %v; want 3, nil", n, err)
 144         }
 145
 146         n, err = CopyN(b, strings.NewReader("foo"), 4) // b has read from
 147         if n != 3 || err != EOF {
 148                 t.Errorf("CopyN(bytes.Buffer, foo, 4) = %d, %v; want 3, EOF", n, err)
 149         }
 150
 151         n, err = CopyN(b, wantedAndErrReader{}, 5)
 152         if n != 5 || err != nil {
 153                 t.Errorf("CopyN(bytes.Buffer, wantedAndErrReader, 5) = %d, %v; want 5, nil", n, err)
 154         }
 155
 156         n, err = CopyN(&noReadFrom{b}, wantedAndErrReader{}, 5)
 157         if n != 5 || err != nil {
 158                 t.Errorf("CopyN(noReadFrom, wantedAndErrReader, 5) = %d, %v; want 5, nil", n, err)
 159         }
 160 }
 161
 162 func TestReadAtLeast(t *testing.T) {
 163         var rb bytes.Buffer
 164         testReadAtLeast(t, &rb)
 165 }
 166
 167 // A version of bytes.Buffer that returns n > 0, err on Read
 168 // when the input is exhausted.
 169 type dataAndErrorBuffer struct {
 170         err error
 171         bytes.Buffer
 172 }
 173
 174 func (r *dataAndErrorBuffer) Read(p []byte) (n int, err error) {
 175         n, err = r.Buffer.Read(p)
 176         if n > 0 && r.Buffer.Len() == 0 && err == nil {
 177                 err = r.err
 178         }
 179         return
 180 }
 181
 182 func TestReadAtLeastWithDataAndEOF(t *testing.T) {
 183         var rb dataAndErrorBuffer
 184         rb.err = EOF
 185         testReadAtLeast(t, &rb)
 186 }
 187
 188 func TestReadAtLeastWithDataAndError(t *testing.T) {
 189         var rb dataAndErrorBuffer
 190         rb.err = fmt.Errorf("fake error")
 191         testReadAtLeast(t, &rb)
 192 }
 193
 194 func testReadAtLeast(t *testing.T, rb ReadWriter) {
 195         rb.Write([]byte("0123"))
 196         buf := make([]byte, 2)
 197         n, err := ReadAtLeast(rb, buf, 2)
 198         if err != nil {
 199                 t.Error(err)
 200         }
 201         n, err = ReadAtLeast(rb, buf, 4)
 202         if err != ErrShortBuffer {
 203                 t.Errorf("expected ErrShortBuffer got %v", err)
 204         }
 205         if n != 0 {
 206                 t.Errorf("expected to have read 0 bytes, got %v", n)
 207         }
 208         n, err = ReadAtLeast(rb, buf, 1)
 209         if err != nil {
 210                 t.Error(err)
 211         }
 212         if n != 2 {
 213                 t.Errorf("expected to have read 2 bytes, got %v", n)
 214         }
 215         n, err = ReadAtLeast(rb, buf, 2)
 216         if err != EOF {
 217                 t.Errorf("expected EOF, got %v", err)
 218         }
 219         if n != 0 {
 220                 t.Errorf("expected to have read 0 bytes, got %v", n)
 221         }
 222         rb.Write([]byte("4"))
 223         n, err = ReadAtLeast(rb, buf, 2)
 224         want := ErrUnexpectedEOF
 225         if rb, ok := rb.(*dataAndErrorBuffer); ok && rb.err != EOF {
 226                 want = rb.err
 227         }
 228         if err != want {
 229                 t.Errorf("expected %v, got %v", want, err)
 230         }
 231         if n != 1 {
 232                 t.Errorf("expected to have read 1 bytes, got %v", n)
 233         }
 234 }
 235
 236 func TestTeeReader(t *testing.T) {
 237         src := []byte("hello, world")
 238         dst := make([]byte, len(src))
 239         rb := bytes.NewBuffer(src)
 240         wb := new(bytes.Buffer)
 241         r := TeeReader(rb, wb)
 242         if n, err := ReadFull(r, dst); err != nil || n != len(src) {
 243                 t.Fatalf("ReadFull(r, dst) = %d, %v; want %d, nil", n, err, len(src))
 244         }
 245         if !bytes.Equal(dst, src) {
 246                 t.Errorf("bytes read = %q want %q", dst, src)
 247         }
 248         if !bytes.Equal(wb.Bytes(), src) {
 249                 t.Errorf("bytes written = %q want %q", wb.Bytes(), src)
 250         }
 251         if n, err := r.Read(dst); n != 0 || err != EOF {
 252                 t.Errorf("r.Read at EOF = %d, %v want 0, EOF", n, err)
 253         }
 254         rb = bytes.NewBuffer(src)
 255         pr, pw := Pipe()
 256         pr.Close()
 257         r = TeeReader(rb, pw)
 258         if n, err := ReadFull(r, dst); n != 0 || err != ErrClosedPipe {
 259                 t.Errorf("closed tee: ReadFull(r, dst) = %d, %v; want 0, EPIPE", n, err)
 260         }
 261 }
 262
 263 func TestSectionReader_ReadAt(t *testing.T) {
 264         dat := "a long sample data, 1234567890"
 265         tests := []struct {
 266                 data   string
 267                 off    int
 268                 n      int
 269                 bufLen int
 270                 at     int
 271                 exp    string
 272                 err    error
 273         }{
 274                 {data: "", off: 0, n: 10, bufLen: 2, at: 0, exp: "", err: EOF},
 275                 {data: dat, off: 0, n: len(dat), bufLen: 0, at: 0, exp: "", err: nil},
 276                 {data: dat, off: len(dat), n: 1, bufLen: 1, at: 0, exp: "", err: EOF},
 277                 {data: dat, off: 0, n: len(dat) + 2, bufLen: len(dat), at: 0, exp: dat, err: nil},
 278                 {data: dat, off: 0, n: len(dat), bufLen: len(dat) / 2, at: 0, exp: dat[:len(dat)/2], err: nil},
 279                 {data: dat, off: 0, n: len(dat), bufLen: len(dat), at: 0, exp: dat, err: nil},
 280                 {data: dat, off: 0, n: len(dat), bufLen: len(dat) / 2, at: 2, exp: dat[2 : 2+len(dat)/2], err: nil},
 281                 {data: dat, off: 3, n: len(dat), bufLen: len(dat) / 2, at: 2, exp: dat[5 : 5+len(dat)/2], err: nil},
 282                 {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},
 283                 {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},
 284         }
 285         for i, tt := range tests {
 286                 r := strings.NewReader(tt.data)
 287                 s := NewSectionReader(r, int64(tt.off), int64(tt.n))
 288                 buf := make([]byte, tt.bufLen)
 289                 if n, err := s.ReadAt(buf, int64(tt.at)); n != len(tt.exp) || string(buf[:n]) != tt.exp || err != tt.err {
 290                         t.Fatalf("%d: ReadAt(%d) = %q, %v; expected %q, %v", i, tt.at, buf[:n], err, tt.exp, tt.err)
 291                 }
 292         }
 293 }
 294
 295 func TestSectionReader_Seek(t *testing.T) {
 296         // Verifies that NewSectionReader's Seeker behaves like bytes.NewReader (which is like strings.NewReader)
 297         br := bytes.NewReader([]byte("foo"))
 298         sr := NewSectionReader(br, 0, int64(len("foo")))
 299
 300         for whence := 0; whence <= 2; whence++ {
 301                 for offset := int64(-3); offset <= 4; offset++ {
 302                         brOff, brErr := br.Seek(offset, whence)
 303                         srOff, srErr := sr.Seek(offset, whence)
 304                         if (brErr != nil) != (srErr != nil) || brOff != srOff {
 305                                 t.Errorf("For whence %d, offset %d: bytes.Reader.Seek = (%v, %v) != SectionReader.Seek = (%v, %v)",
 306                                         whence, offset, brOff, brErr, srErr, srOff)
 307                         }
 308                 }
 309         }
 310
 311         // And verify we can just seek past the end and get an EOF
 312         got, err := sr.Seek(100, 0)
 313         if err != nil || got != 100 {
 314                 t.Errorf("Seek = %v, %v; want 100, nil", got, err)
 315         }
 316
 317         n, err := sr.Read(make([]byte, 10))
 318         if n != 0 || err != EOF {
 319                 t.Errorf("Read = %v, %v; want 0, EOF", n, err)
 320         }
 321 }