libgo/go/strings/reader_test.go

   1 // Copyright 2012 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 strings_test
   6
   7 import (
   8         "bytes"
   9         "fmt"
  10         "io"
  11         "strings"
  12         "sync"
  13         "testing"
  14 )
  15
  16 func TestReader(t *testing.T) {
  17         r := strings.NewReader("0123456789")
  18         tests := []struct {
  19                 off     int64
  20                 seek    int
  21                 n       int
  22                 want    string
  23                 wantpos int64
  24                 readerr error
  25                 seekerr string
  26         }{
  27                 {seek: io.SeekStart, off: 0, n: 20, want: "0123456789"},
  28                 {seek: io.SeekStart, off: 1, n: 1, want: "1"},
  29                 {seek: io.SeekCurrent, off: 1, wantpos: 3, n: 2, want: "34"},
  30                 {seek: io.SeekStart, off: -1, seekerr: "strings.Reader.Seek: negative position"},
  31                 {seek: io.SeekStart, off: 1 << 33, wantpos: 1 << 33, readerr: io.EOF},
  32                 {seek: io.SeekCurrent, off: 1, wantpos: 1<<33 + 1, readerr: io.EOF},
  33                 {seek: io.SeekStart, n: 5, want: "01234"},
  34                 {seek: io.SeekCurrent, n: 5, want: "56789"},
  35                 {seek: io.SeekEnd, off: -1, n: 1, wantpos: 9, want: "9"},
  36         }
  37
  38         for i, tt := range tests {
  39                 pos, err := r.Seek(tt.off, tt.seek)
  40                 if err == nil && tt.seekerr != "" {
  41                         t.Errorf("%d. want seek error %q", i, tt.seekerr)
  42                         continue
  43                 }
  44                 if err != nil && err.Error() != tt.seekerr {
  45                         t.Errorf("%d. seek error = %q; want %q", i, err.Error(), tt.seekerr)
  46                         continue
  47                 }
  48                 if tt.wantpos != 0 && tt.wantpos != pos {
  49                         t.Errorf("%d. pos = %d, want %d", i, pos, tt.wantpos)
  50                 }
  51                 buf := make([]byte, tt.n)
  52                 n, err := r.Read(buf)
  53                 if err != tt.readerr {
  54                         t.Errorf("%d. read = %v; want %v", i, err, tt.readerr)
  55                         continue
  56                 }
  57                 got := string(buf[:n])
  58                 if got != tt.want {
  59                         t.Errorf("%d. got %q; want %q", i, got, tt.want)
  60                 }
  61         }
  62 }
  63
  64 func TestReadAfterBigSeek(t *testing.T) {
  65         r := strings.NewReader("0123456789")
  66         if _, err := r.Seek(1<<31+5, io.SeekStart); err != nil {
  67                 t.Fatal(err)
  68         }
  69         if n, err := r.Read(make([]byte, 10)); n != 0 || err != io.EOF {
  70                 t.Errorf("Read = %d, %v; want 0, EOF", n, err)
  71         }
  72 }
  73
  74 func TestReaderAt(t *testing.T) {
  75         r := strings.NewReader("0123456789")
  76         tests := []struct {
  77                 off     int64
  78                 n       int
  79                 want    string
  80                 wanterr any
  81         }{
  82                 {0, 10, "0123456789", nil},
  83                 {1, 10, "123456789", io.EOF},
  84                 {1, 9, "123456789", nil},
  85                 {11, 10, "", io.EOF},
  86                 {0, 0, "", nil},
  87                 {-1, 0, "", "strings.Reader.ReadAt: negative offset"},
  88         }
  89         for i, tt := range tests {
  90                 b := make([]byte, tt.n)
  91                 rn, err := r.ReadAt(b, tt.off)
  92                 got := string(b[:rn])
  93                 if got != tt.want {
  94                         t.Errorf("%d. got %q; want %q", i, got, tt.want)
  95                 }
  96                 if fmt.Sprintf("%v", err) != fmt.Sprintf("%v", tt.wanterr) {
  97                         t.Errorf("%d. got error = %v; want %v", i, err, tt.wanterr)
  98                 }
  99         }
 100 }
 101
 102 func TestReaderAtConcurrent(t *testing.T) {
 103         // Test for the race detector, to verify ReadAt doesn't mutate
 104         // any state.
 105         r := strings.NewReader("0123456789")
 106         var wg sync.WaitGroup
 107         for i := 0; i < 5; i++ {
 108                 wg.Add(1)
 109                 go func(i int) {
 110                         defer wg.Done()
 111                         var buf [1]byte
 112                         r.ReadAt(buf[:], int64(i))
 113                 }(i)
 114         }
 115         wg.Wait()
 116 }
 117
 118 func TestEmptyReaderConcurrent(t *testing.T) {
 119         // Test for the race detector, to verify a Read that doesn't yield any bytes
 120         // is okay to use from multiple goroutines. This was our historic behavior.
 121         // See golang.org/issue/7856
 122         r := strings.NewReader("")
 123         var wg sync.WaitGroup
 124         for i := 0; i < 5; i++ {
 125                 wg.Add(2)
 126                 go func() {
 127                         defer wg.Done()
 128                         var buf [1]byte
 129                         r.Read(buf[:])
 130                 }()
 131                 go func() {
 132                         defer wg.Done()
 133                         r.Read(nil)
 134                 }()
 135         }
 136         wg.Wait()
 137 }
 138
 139 func TestWriteTo(t *testing.T) {
 140         const str = "0123456789"
 141         for i := 0; i <= len(str); i++ {
 142                 s := str[i:]
 143                 r := strings.NewReader(s)
 144                 var b bytes.Buffer
 145                 n, err := r.WriteTo(&b)
 146                 if expect := int64(len(s)); n != expect {
 147                         t.Errorf("got %v; want %v", n, expect)
 148                 }
 149                 if err != nil {
 150                         t.Errorf("for length %d: got error = %v; want nil", len(s), err)
 151                 }
 152                 if b.String() != s {
 153                         t.Errorf("got string %q; want %q", b.String(), s)
 154                 }
 155                 if r.Len() != 0 {
 156                         t.Errorf("reader contains %v bytes; want 0", r.Len())
 157                 }
 158         }
 159 }
 160
 161 // tests that Len is affected by reads, but Size is not.
 162 func TestReaderLenSize(t *testing.T) {
 163         r := strings.NewReader("abc")
 164         io.CopyN(io.Discard, r, 1)
 165         if r.Len() != 2 {
 166                 t.Errorf("Len = %d; want 2", r.Len())
 167         }
 168         if r.Size() != 3 {
 169                 t.Errorf("Size = %d; want 3", r.Size())
 170         }
 171 }
 172
 173 func TestReaderReset(t *testing.T) {
 174         r := strings.NewReader("世界")
 175         if _, _, err := r.ReadRune(); err != nil {
 176                 t.Errorf("ReadRune: unexpected error: %v", err)
 177         }
 178
 179         const want = "abcdef"
 180         r.Reset(want)
 181         if err := r.UnreadRune(); err == nil {
 182                 t.Errorf("UnreadRune: expected error, got nil")
 183         }
 184         buf, err := io.ReadAll(r)
 185         if err != nil {
 186                 t.Errorf("ReadAll: unexpected error: %v", err)
 187         }
 188         if got := string(buf); got != want {
 189                 t.Errorf("ReadAll: got %q, want %q", got, want)
 190         }
 191 }
 192
 193 func TestReaderZero(t *testing.T) {
 194         if l := (&strings.Reader{}).Len(); l != 0 {
 195                 t.Errorf("Len: got %d, want 0", l)
 196         }
 197
 198         if n, err := (&strings.Reader{}).Read(nil); n != 0 || err != io.EOF {
 199                 t.Errorf("Read: got %d, %v; want 0, io.EOF", n, err)
 200         }
 201
 202         if n, err := (&strings.Reader{}).ReadAt(nil, 11); n != 0 || err != io.EOF {
 203                 t.Errorf("ReadAt: got %d, %v; want 0, io.EOF", n, err)
 204         }
 205
 206         if b, err := (&strings.Reader{}).ReadByte(); b != 0 || err != io.EOF {
 207                 t.Errorf("ReadByte: got %d, %v; want 0, io.EOF", b, err)
 208         }
 209
 210         if ch, size, err := (&strings.Reader{}).ReadRune(); ch != 0 || size != 0 || err != io.EOF {
 211                 t.Errorf("ReadRune: got %d, %d, %v; want 0, 0, io.EOF", ch, size, err)
 212         }
 213
 214         if offset, err := (&strings.Reader{}).Seek(11, io.SeekStart); offset != 11 || err != nil {
 215                 t.Errorf("Seek: got %d, %v; want 11, nil", offset, err)
 216         }
 217
 218         if s := (&strings.Reader{}).Size(); s != 0 {
 219                 t.Errorf("Size: got %d, want 0", s)
 220         }
 221
 222         if (&strings.Reader{}).UnreadByte() == nil {
 223                 t.Errorf("UnreadByte: got nil, want error")
 224         }
 225
 226         if (&strings.Reader{}).UnreadRune() == nil {
 227                 t.Errorf("UnreadRune: got nil, want error")
 228         }
 229
 230         if n, err := (&strings.Reader{}).WriteTo(io.Discard); n != 0 || err != nil {
 231                 t.Errorf("WriteTo: got %d, %v; want 0, nil", n, err)
 232         }
 233 }