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Source file src/bytes/reader_test.go

Documentation: bytes

     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 bytes_test
     6  
     7  import (
     8  	. "bytes"
     9  	"fmt"
    10  	"io"
    11  	"io/ioutil"
    12  	"sync"
    13  	"testing"
    14  )
    15  
    16  func TestReader(t *testing.T) {
    17  	r := NewReader([]byte("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: "bytes.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 := NewReader([]byte("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 := NewReader([]byte("0123456789"))
    76  	tests := []struct {
    77  		off     int64
    78  		n       int
    79  		want    string
    80  		wanterr interface{}
    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, "", "bytes.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 := NewReader([]byte("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 := NewReader([]byte{})
   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 TestReaderWriteTo(t *testing.T) {
   140  	for i := 0; i < 30; i += 3 {
   141  		var l int
   142  		if i > 0 {
   143  			l = len(testString) / i
   144  		}
   145  		s := testString[:l]
   146  		r := NewReader(testBytes[:l])
   147  		var b Buffer
   148  		n, err := r.WriteTo(&b)
   149  		if expect := int64(len(s)); n != expect {
   150  			t.Errorf("got %v; want %v", n, expect)
   151  		}
   152  		if err != nil {
   153  			t.Errorf("for length %d: got error = %v; want nil", l, err)
   154  		}
   155  		if b.String() != s {
   156  			t.Errorf("got string %q; want %q", b.String(), s)
   157  		}
   158  		if r.Len() != 0 {
   159  			t.Errorf("reader contains %v bytes; want 0", r.Len())
   160  		}
   161  	}
   162  }
   163  
   164  func TestReaderLen(t *testing.T) {
   165  	const data = "hello world"
   166  	r := NewReader([]byte(data))
   167  	if got, want := r.Len(), 11; got != want {
   168  		t.Errorf("r.Len(): got %d, want %d", got, want)
   169  	}
   170  	if n, err := r.Read(make([]byte, 10)); err != nil || n != 10 {
   171  		t.Errorf("Read failed: read %d %v", n, err)
   172  	}
   173  	if got, want := r.Len(), 1; got != want {
   174  		t.Errorf("r.Len(): got %d, want %d", got, want)
   175  	}
   176  	if n, err := r.Read(make([]byte, 1)); err != nil || n != 1 {
   177  		t.Errorf("Read failed: read %d %v; want 1, nil", n, err)
   178  	}
   179  	if got, want := r.Len(), 0; got != want {
   180  		t.Errorf("r.Len(): got %d, want %d", got, want)
   181  	}
   182  }
   183  
   184  var UnreadRuneErrorTests = []struct {
   185  	name string
   186  	f    func(*Reader)
   187  }{
   188  	{"Read", func(r *Reader) { r.Read([]byte{0}) }},
   189  	{"ReadByte", func(r *Reader) { r.ReadByte() }},
   190  	{"UnreadRune", func(r *Reader) { r.UnreadRune() }},
   191  	{"Seek", func(r *Reader) { r.Seek(0, io.SeekCurrent) }},
   192  	{"WriteTo", func(r *Reader) { r.WriteTo(&Buffer{}) }},
   193  }
   194  
   195  func TestUnreadRuneError(t *testing.T) {
   196  	for _, tt := range UnreadRuneErrorTests {
   197  		reader := NewReader([]byte("0123456789"))
   198  		if _, _, err := reader.ReadRune(); err != nil {
   199  			// should not happen
   200  			t.Fatal(err)
   201  		}
   202  		tt.f(reader)
   203  		err := reader.UnreadRune()
   204  		if err == nil {
   205  			t.Errorf("Unreading after %s: expected error", tt.name)
   206  		}
   207  	}
   208  }
   209  
   210  func TestReaderDoubleUnreadRune(t *testing.T) {
   211  	buf := NewBuffer([]byte("groucho"))
   212  	if _, _, err := buf.ReadRune(); err != nil {
   213  		// should not happen
   214  		t.Fatal(err)
   215  	}
   216  	if err := buf.UnreadByte(); err != nil {
   217  		// should not happen
   218  		t.Fatal(err)
   219  	}
   220  	if err := buf.UnreadByte(); err == nil {
   221  		t.Fatal("UnreadByte: expected error, got nil")
   222  	}
   223  }
   224  
   225  // verify that copying from an empty reader always has the same results,
   226  // regardless of the presence of a WriteTo method.
   227  func TestReaderCopyNothing(t *testing.T) {
   228  	type nErr struct {
   229  		n   int64
   230  		err error
   231  	}
   232  	type justReader struct {
   233  		io.Reader
   234  	}
   235  	type justWriter struct {
   236  		io.Writer
   237  	}
   238  	discard := justWriter{ioutil.Discard} // hide ReadFrom
   239  
   240  	var with, withOut nErr
   241  	with.n, with.err = io.Copy(discard, NewReader(nil))
   242  	withOut.n, withOut.err = io.Copy(discard, justReader{NewReader(nil)})
   243  	if with != withOut {
   244  		t.Errorf("behavior differs: with = %#v; without: %#v", with, withOut)
   245  	}
   246  }
   247  
   248  // tests that Len is affected by reads, but Size is not.
   249  func TestReaderLenSize(t *testing.T) {
   250  	r := NewReader([]byte("abc"))
   251  	io.CopyN(ioutil.Discard, r, 1)
   252  	if r.Len() != 2 {
   253  		t.Errorf("Len = %d; want 2", r.Len())
   254  	}
   255  	if r.Size() != 3 {
   256  		t.Errorf("Size = %d; want 3", r.Size())
   257  	}
   258  }
   259  
   260  func TestReaderReset(t *testing.T) {
   261  	r := NewReader([]byte("世界"))
   262  	if _, _, err := r.ReadRune(); err != nil {
   263  		t.Errorf("ReadRune: unexpected error: %v", err)
   264  	}
   265  
   266  	const want = "abcdef"
   267  	r.Reset([]byte(want))
   268  	if err := r.UnreadRune(); err == nil {
   269  		t.Errorf("UnreadRune: expected error, got nil")
   270  	}
   271  	buf, err := ioutil.ReadAll(r)
   272  	if err != nil {
   273  		t.Errorf("ReadAll: unexpected error: %v", err)
   274  	}
   275  	if got := string(buf); got != want {
   276  		t.Errorf("ReadAll: got %q, want %q", got, want)
   277  	}
   278  }
   279  

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