1 files changed, 153 insertions, 0 deletions
diff --git a/src/testing/iotest/logger_test.go b/src/testing/iotest/logger_test.go
new file mode 100644
index 0000000..7a7d0aa
--- /dev/null
+++ b/src/testing/iotest/logger_test.go
@@ -0,0 +1,153 @@
+// Copyright 2019 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 (
+	"bytes"
+	"errors"
+	"fmt"
+	"log"
+	"strings"
+	"testing"
+)
+
+type errWriter struct {
+	err error
+}
+
+func (w errWriter) Write([]byte) (int, error) {
+	return 0, w.err
+}
+
+func TestWriteLogger(t *testing.T) {
+	olw := log.Writer()
+	olf := log.Flags()
+	olp := log.Prefix()
+
+	// Revert the original log settings before we exit.
+	defer func() {
+		log.SetFlags(olf)
+		log.SetPrefix(olp)
+		log.SetOutput(olw)
+	}()
+
+	lOut := new(strings.Builder)
+	log.SetPrefix("lw: ")
+	log.SetOutput(lOut)
+	log.SetFlags(0)
+
+	lw := new(strings.Builder)
+	wl := NewWriteLogger("write:", lw)
+	if _, err := wl.Write([]byte("Hello, World!")); err != nil {
+		t.Fatalf("Unexpectedly failed to write: %v", err)
+	}
+
+	if g, w := lw.String(), "Hello, World!"; g != w {
+		t.Errorf("WriteLogger mismatch\n\tgot:  %q\n\twant: %q", g, w)
+	}
+	wantLogWithHex := fmt.Sprintf("lw: write: %x\n", "Hello, World!")
+	if g, w := lOut.String(), wantLogWithHex; g != w {
+		t.Errorf("WriteLogger mismatch\n\tgot:  %q\n\twant: %q", g, w)
+	}
+}
+
+func TestWriteLogger_errorOnWrite(t *testing.T) {
+	olw := log.Writer()
+	olf := log.Flags()
+	olp := log.Prefix()
+
+	// Revert the original log settings before we exit.
+	defer func() {
+		log.SetFlags(olf)
+		log.SetPrefix(olp)
+		log.SetOutput(olw)
+	}()
+
+	lOut := new(strings.Builder)
+	log.SetPrefix("lw: ")
+	log.SetOutput(lOut)
+	log.SetFlags(0)
+
+	lw := errWriter{err: errors.New("Write Error!")}
+	wl := NewWriteLogger("write:", lw)
+	if _, err := wl.Write([]byte("Hello, World!")); err == nil {
+		t.Fatalf("Unexpectedly succeeded to write: %v", err)
+	}
+
+	wantLogWithHex := fmt.Sprintf("lw: write: %x: %v\n", "", "Write Error!")
+	if g, w := lOut.String(), wantLogWithHex; g != w {
+		t.Errorf("WriteLogger mismatch\n\tgot:  %q\n\twant: %q", g, w)
+	}
+}
+
+func TestReadLogger(t *testing.T) {
+	olw := log.Writer()
+	olf := log.Flags()
+	olp := log.Prefix()
+
+	// Revert the original log settings before we exit.
+	defer func() {
+		log.SetFlags(olf)
+		log.SetPrefix(olp)
+		log.SetOutput(olw)
+	}()
+
+	lOut := new(strings.Builder)
+	log.SetPrefix("lr: ")
+	log.SetOutput(lOut)
+	log.SetFlags(0)
+
+	data := []byte("Hello, World!")
+	p := make([]byte, len(data))
+	lr := bytes.NewReader(data)
+	rl := NewReadLogger("read:", lr)
+
+	n, err := rl.Read(p)
+	if err != nil {
+		t.Fatalf("Unexpectedly failed to read: %v", err)
+	}
+
+	if g, w := p[:n], data; !bytes.Equal(g, w) {
+		t.Errorf("ReadLogger mismatch\n\tgot:  %q\n\twant: %q", g, w)
+	}
+
+	wantLogWithHex := fmt.Sprintf("lr: read: %x\n", "Hello, World!")
+	if g, w := lOut.String(), wantLogWithHex; g != w {
+		t.Errorf("ReadLogger mismatch\n\tgot:  %q\n\twant: %q", g, w)
+	}
+}
+
+func TestReadLogger_errorOnRead(t *testing.T) {
+	olw := log.Writer()
+	olf := log.Flags()
+	olp := log.Prefix()
+
+	// Revert the original log settings before we exit.
+	defer func() {
+		log.SetFlags(olf)
+		log.SetPrefix(olp)
+		log.SetOutput(olw)
+	}()
+
+	lOut := new(strings.Builder)
+	log.SetPrefix("lr: ")
+	log.SetOutput(lOut)
+	log.SetFlags(0)
+
+	data := []byte("Hello, World!")
+	p := make([]byte, len(data))
+
+	lr := ErrReader(errors.New("io failure"))
+	rl := NewReadLogger("read", lr)
+	n, err := rl.Read(p)
+	if err == nil {
+		t.Fatalf("Unexpectedly succeeded to read: %v", err)
+	}
+
+	wantLogWithHex := fmt.Sprintf("lr: read %x: io failure\n", p[:n])
+	if g, w := lOut.String(), wantLogWithHex; g != w {
+		t.Errorf("ReadLogger mismatch\n\tgot:  %q\n\twant: %q", g, w)
+	}
+}