bytes/reader_test

bytes/bytes.go

@@ -31,18 +31,21 @@ type Reader struct {
 
 // NewReader create a readonly stream for byte slice:
 //
-//	 var slice []byte
-//	 ...
-//	 r := bytes.NewReader(slice)
-//	 ...
-//	 r.Seek(0, 0) // r.SeekToBegin()
-//	 ...
+//	var slice []byte
+//	...
+//	r := bytes.NewReader(slice)
+//	...
+//	r.Seek(0, 0) // r.SeekToBegin()
+//	...
 //
 // Unlike the standard library's bytes.Reader, the returned Reader supports Seek.
 func NewReader(val []byte) *Reader {
 	return &Reader{val, 0}
 }
 
+// Size returns the original length of the underlying byte slice.
+func (r *Reader) Size() int64 { return int64(len(r.b)) }
+
 func (r *Reader) Len() int {
 	if r.off >= len(r.b) {
 		return 0
@@ -61,10 +64,10 @@ func (r *Reader) SeekToBegin() (err error) {
 
 func (r *Reader) Seek(offset int64, whence int) (ret int64, err error) {
 	switch whence {
-	case 0:
-	case 1:
+	case io.SeekStart:
+	case io.SeekCurrent:
 		offset += int64(r.off)
-	case 2:
+	case io.SeekEnd:
 		offset += int64(len(r.b))
 	default:
 		err = syscall.EINVAL
@@ -107,10 +110,10 @@ type Writer struct {
 
 // NewWriter NewWriter creates a write stream with a limited capacity:
 //
-//	 slice := make([]byte, 1024)
-//	 w := bytes.NewWriter(slice)
-//	 ...
-//	 writtenData := w.Bytes()
+//	slice := make([]byte, 1024)
+//	w := bytes.NewWriter(slice)
+//	...
+//	writtenData := w.Bytes()
 //
 // If we write more than 1024 bytes of data to w, the excess data will be discarded.
 func NewWriter(buff []byte) *Writer {
@@ -149,13 +152,12 @@ type Buffer struct {
 // NewBuffer creates a random read/write memory file that supports ReadAt/WriteAt
 // methods instead of Read/Write:
 //
-//	 b := bytes.NewBuffer()
-//	 b.Truncate(100)
-//	 b.WriteAt([]byte("hello"), 100)
-//	 slice := make([]byte, 105)
-//	 n, err := b.ReadAt(slice, 0)
-//	 ...
-//
+//	b := bytes.NewBuffer()
+//	b.Truncate(100)
+//	b.WriteAt([]byte("hello"), 100)
+//	slice := make([]byte, 105)
+//	n, err := b.ReadAt(slice, 0)
+//	...
 func NewBuffer() *Buffer {
 	return new(Buffer)
 }

bytes/reader_test.go

@@ -0,0 +1,178 @@
+package bytes_test
+
+import (
+	"io"
+	"sync"
+	"syscall"
+	"testing"
+
+	. "github.com/qiniu/x/bytes"
+)
+
+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: "invalid argument"},
+		{seek: io.SeekStart, off: 1 << 33, wantpos: 10, readerr: nil},
+		{seek: io.SeekCurrent, off: 1, wantpos: 10, readerr: nil},
+		{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 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 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)
+	}
+}
+
+// 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{io.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(io.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 TestReaderZero(t *testing.T) {
+	if l := (&Reader{}).Len(); l != 0 {
+		t.Errorf("Len: got %d, want 0", l)
+	}
+
+	if e := (&Reader{}).SeekToBegin(); e != nil {
+		t.Errorf("SeekToBegin: got %v, want nil", e)
+	}
+
+	if _, e := (&Reader{}).Seek(0, 4); e != syscall.EINVAL {
+		t.Errorf("SeekToBegin: got %v, want EINVAL", e)
+	}
+
+	if e := (&Reader{}).Close(); e != nil {
+		t.Errorf("Close: got %v, want nil", e)
+	}
+
+	if v := (&Reader{}).Bytes(); v != nil {
+		t.Errorf("Bytes: got %v, want nil", nil)
+	}
+
+	if n, err := (&Reader{}).Read(nil); n != 0 || err != nil {
+		t.Errorf("Read: got %d, %v; want 0, io.EOF", n, err)
+	}
+
+	if offset, err := (&Reader{}).Seek(11, io.SeekStart); offset != 0 || err != nil {
+		t.Errorf("Seek: got %d, %v; want 11, nil", offset, err)
+	}
+
+	if s := (&Reader{}).Size(); s != 0 {
+		t.Errorf("Size: got %d, want 0", s)
+	}
+}