3 files changed, 177 insertions, 0 deletions
diff --git a/src/testing/iotest/logger.go b/src/testing/iotest/logger.go
new file mode 100644
index 000000000..1475d9b0c
--- /dev/null
+++ b/src/testing/iotest/logger.go
@@ -0,0 +1,54 @@
+// Copyright 2009 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 iotest
+
+import (
+	"io"
+	"log"
+)
+
+type writeLogger struct {
+	prefix string
+	w      io.Writer
+}
+
+func (l *writeLogger) Write(p []byte) (n int, err error) {
+	n, err = l.w.Write(p)
+	if err != nil {
+		log.Printf("%s %x: %v", l.prefix, p[0:n], err)
+	} else {
+		log.Printf("%s %x", l.prefix, p[0:n])
+	}
+	return
+}
+
+// NewWriteLogger returns a writer that behaves like w except
+// that it logs (using log.Printf) each write to standard error,
+// printing the prefix and the hexadecimal data written.
+func NewWriteLogger(prefix string, w io.Writer) io.Writer {
+	return &writeLogger{prefix, w}
+}
+
+type readLogger struct {
+	prefix string
+	r      io.Reader
+}
+
+func (l *readLogger) Read(p []byte) (n int, err error) {
+	n, err = l.r.Read(p)
+	if err != nil {
+		log.Printf("%s %x: %v", l.prefix, p[0:n], err)
+	} else {
+		log.Printf("%s %x", l.prefix, p[0:n])
+	}
+	return
+}
+
+// NewReadLogger returns a reader that behaves like r except
+// that it logs (using log.Print) each read to standard error,
+// printing the prefix and the hexadecimal data written.
+func NewReadLogger(prefix string, r io.Reader) io.Reader {
+	return &readLogger{prefix, r}
+}
diff --git a/src/testing/iotest/reader.go b/src/testing/iotest/reader.go
new file mode 100644
index 000000000..a5bccca90
--- /dev/null
+++ b/src/testing/iotest/reader.go
@@ -0,0 +1,88 @@
+// Copyright 2009 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 iotest implements Readers and Writers useful mainly for testing.
+package iotest
+
+import (
+	"errors"
+	"io"
+)
+
+// OneByteReader returns a Reader that implements
+// each non-empty Read by reading one byte from r.
+func OneByteReader(r io.Reader) io.Reader { return &oneByteReader{r} }
+
+type oneByteReader struct {
+	r io.Reader
+}
+
+func (r *oneByteReader) Read(p []byte) (int, error) {
+	if len(p) == 0 {
+		return 0, nil
+	}
+	return r.r.Read(p[0:1])
+}
+
+// HalfReader returns a Reader that implements Read
+// by reading half as many requested bytes from r.
+func HalfReader(r io.Reader) io.Reader { return &halfReader{r} }
+
+type halfReader struct {
+	r io.Reader
+}
+
+func (r *halfReader) Read(p []byte) (int, error) {
+	return r.r.Read(p[0 : (len(p)+1)/2])
+}
+
+// DataErrReader changes the way errors are handled by a Reader. Normally, a
+// Reader returns an error (typically EOF) from the first Read call after the
+// last piece of data is read. DataErrReader wraps a Reader and changes its
+// behavior so the final error is returned along with the final data, instead
+// of in the first call after the final data.
+func DataErrReader(r io.Reader) io.Reader { return &dataErrReader{r, nil, make([]byte, 1024)} }
+
+type dataErrReader struct {
+	r      io.Reader
+	unread []byte
+	data   []byte
+}
+
+func (r *dataErrReader) Read(p []byte) (n int, err error) {
+	// loop because first call needs two reads:
+	// one to get data and a second to look for an error.
+	for {
+		if len(r.unread) == 0 {
+			n1, err1 := r.r.Read(r.data)
+			r.unread = r.data[0:n1]
+			err = err1
+		}
+		if n > 0 || err != nil {
+			break
+		}
+		n = copy(p, r.unread)
+		r.unread = r.unread[n:]
+	}
+	return
+}
+
+var ErrTimeout = errors.New("timeout")
+
+// TimeoutReader returns ErrTimeout on the second read
+// with no data.  Subsequent calls to read succeed.
+func TimeoutReader(r io.Reader) io.Reader { return &timeoutReader{r, 0} }
+
+type timeoutReader struct {
+	r     io.Reader
+	count int
+}
+
+func (r *timeoutReader) Read(p []byte) (int, error) {
+	r.count++
+	if r.count == 2 {
+		return 0, ErrTimeout
+	}
+	return r.r.Read(p)
+}
diff --git a/src/testing/iotest/writer.go b/src/testing/iotest/writer.go
new file mode 100644
index 000000000..af61ab858
--- /dev/null
+++ b/src/testing/iotest/writer.go
@@ -0,0 +1,35 @@
+// Copyright 2009 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 iotest
+
+import "io"
+
+// TruncateWriter returns a Writer that writes to w
+// but stops silently after n bytes.
+func TruncateWriter(w io.Writer, n int64) io.Writer {
+	return &truncateWriter{w, n}
+}
+
+type truncateWriter struct {
+	w io.Writer
+	n int64
+}
+
+func (t *truncateWriter) Write(p []byte) (n int, err error) {
+	if t.n <= 0 {
+		return len(p), nil
+	}
+	// real write
+	n = len(p)
+	if int64(n) > t.n {
+		n = int(t.n)
+	}
+	n, err = t.w.Write(p[0:n])
+	t.n -= int64(n)
+	if err == nil {
+		n = len(p)
+	}
+	return
+}