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Source file src/bytes/reader_test.go

Documentation: bytes

  // 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"
  	"io/ioutil"
  	"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 interface{}
  	}{
  		{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(data) / i
  		}
  		s := data[: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{ioutil.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(ioutil.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 := ioutil.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)
  	}
  }
  

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