1 files changed, 54 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}
+}