encoding: use strings.Builder

Change-Id: Ib07699df8ea41fd8d1bca8ad050859fac24623de
Reviewed-on: https://go-review.googlesource.com/c/go/+/428258
Reviewed-by: Robert Griesemer <gri@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>

src/encoding/ascii85/ascii85_test.go

@@ -75,7 +75,7 @@ func TestEncode(t *testing.T) {
 
 func TestEncoder(t *testing.T) {
 	for _, p := range pairs {
-		bb := &bytes.Buffer{}
+		bb := &strings.Builder{}
 		encoder := NewEncoder(bb)
 		encoder.Write([]byte(p.decoded))
 		encoder.Close()
@@ -86,7 +86,7 @@ func TestEncoder(t *testing.T) {
 func TestEncoderBuffering(t *testing.T) {
 	input := []byte(bigtest.decoded)
 	for bs := 1; bs <= 12; bs++ {
-		bb := &bytes.Buffer{}
+		bb := &strings.Builder{}
 		encoder := NewEncoder(bb)
 		for pos := 0; pos < len(input); pos += bs {
 			end := pos + bs

src/encoding/base32/base32_test.go

@@ -60,7 +60,7 @@ func TestEncode(t *testing.T) {
 
 func TestEncoder(t *testing.T) {
 	for _, p := range pairs {
-		bb := &bytes.Buffer{}
+		bb := &strings.Builder{}
 		encoder := NewEncoder(StdEncoding, bb)
 		encoder.Write([]byte(p.decoded))
 		encoder.Close()
@@ -71,7 +71,7 @@ func TestEncoder(t *testing.T) {
 func TestEncoderBuffering(t *testing.T) {
 	input := []byte(bigtest.decoded)
 	for bs := 1; bs <= 12; bs++ {
-		bb := &bytes.Buffer{}
+		bb := &strings.Builder{}
 		encoder := NewEncoder(StdEncoding, bb)
 		for pos := 0; pos < len(input); pos += bs {
 			end := pos + bs
@@ -737,7 +737,7 @@ func TestWithoutPaddingClose(t *testing.T) {
 	for _, encoding := range encodings {
 		for _, testpair := range pairs {
 
-			var buf bytes.Buffer
+			var buf strings.Builder
 			encoder := NewEncoder(encoding, &buf)
 			encoder.Write([]byte(testpair.decoded))
 			encoder.Close()

src/encoding/base64/base64_test.go

@@ -119,7 +119,7 @@ func TestEncode(t *testing.T) {
 
 func TestEncoder(t *testing.T) {
 	for _, p := range pairs {
-		bb := &bytes.Buffer{}
+		bb := &strings.Builder{}
 		encoder := NewEncoder(StdEncoding, bb)
 		encoder.Write([]byte(p.decoded))
 		encoder.Close()
@@ -130,7 +130,7 @@ func TestEncoder(t *testing.T) {
 func TestEncoderBuffering(t *testing.T) {
 	input := []byte(bigtest.decoded)
 	for bs := 1; bs <= 12; bs++ {
-		bb := &bytes.Buffer{}
+		bb := &strings.Builder{}
 		encoder := NewEncoder(StdEncoding, bb)
 		for pos := 0; pos < len(input); pos += bs {
 			end := pos + bs

src/encoding/csv/writer_test.go

@@ -7,6 +7,7 @@ package csv
 import (
 	"bytes"
 	"errors"
+	"strings"
 	"testing"
 )
 
@@ -50,7 +51,7 @@ var writeTests = []struct {
 
 func TestWrite(t *testing.T) {
 	for n, tt := range writeTests {
-		b := &bytes.Buffer{}
+		b := &strings.Builder{}
 		f := NewWriter(b)
 		f.UseCRLF = tt.UseCRLF
 		if tt.Comma != 0 {

src/encoding/gob/codec_test.go

@@ -1467,7 +1467,7 @@ func TestFuzzOneByte(t *testing.T) {
 		t.Skipf("disabled; run with -gob.fuzz to enable")
 	}
 
-	buf := new(bytes.Buffer)
+	buf := new(strings.Builder)
 	Register(OnTheFly{})
 	dt := newDT()
 	if err := NewEncoder(buf).Encode(dt); err != nil {

src/encoding/hex/hex_test.go

@@ -188,7 +188,7 @@ func TestDumper(t *testing.T) {
 }
 
 func TestDumper_doubleclose(t *testing.T) {
-	var out bytes.Buffer
+	var out strings.Builder
 	dumper := Dumper(&out)
 
 	dumper.Write([]byte(`gopher`))
@@ -204,7 +204,7 @@ func TestDumper_doubleclose(t *testing.T) {
 }
 
 func TestDumper_earlyclose(t *testing.T) {
-	var out bytes.Buffer
+	var out strings.Builder
 	dumper := Dumper(&out)
 
 	dumper.Close()

src/encoding/json/stream_test.go

@@ -42,7 +42,7 @@ false
 
 func TestEncoder(t *testing.T) {
 	for i := 0; i <= len(streamTest); i++ {
-		var buf bytes.Buffer
+		var buf strings.Builder
 		enc := NewEncoder(&buf)
 		// Check that enc.SetIndent("", "") turns off indentation.
 		enc.SetIndent(">", ".")
@@ -115,7 +115,7 @@ false
 `
 
 func TestEncoderIndent(t *testing.T) {
-	var buf bytes.Buffer
+	var buf strings.Builder
 	enc := NewEncoder(&buf)
 	enc.SetIndent(">", ".")
 	for _, v := range streamTest {
@@ -185,7 +185,7 @@ func TestEncoderSetEscapeHTML(t *testing.T) {
 			`{"bar":"\"<html>foobar</html>\""}`,
 		},
 	} {
-		var buf bytes.Buffer
+		var buf strings.Builder
 		enc := NewEncoder(&buf)
 		if err := enc.Encode(tt.v); err != nil {
 			t.Errorf("Encode(%s): %s", tt.name, err)

src/encoding/xml/marshal_test.go

@@ -1894,13 +1894,13 @@ func TestMarshalWriteIOErrors(t *testing.T) {
 }
 
 func TestMarshalFlush(t *testing.T) {
-	var buf bytes.Buffer
+	var buf strings.Builder
 	enc := NewEncoder(&buf)
 	if err := enc.EncodeToken(CharData("hello world")); err != nil {
 		t.Fatalf("enc.EncodeToken: %v", err)
 	}
 	if buf.Len() > 0 {
-		t.Fatalf("enc.EncodeToken caused actual write: %q", buf.Bytes())
+		t.Fatalf("enc.EncodeToken caused actual write: %q", buf.String())
 	}
 	if err := enc.Flush(); err != nil {
 		t.Fatalf("enc.Flush: %v", err)
@@ -2317,7 +2317,7 @@ var encodeTokenTests = []struct {
 func TestEncodeToken(t *testing.T) {
 loop:
 	for i, tt := range encodeTokenTests {
-		var buf bytes.Buffer
+		var buf strings.Builder
 		enc := NewEncoder(&buf)
 		var err error
 		for j, tok := range tt.toks {
@@ -2437,7 +2437,7 @@ func TestIsValidDirective(t *testing.T) {
 
 // Issue 11719. EncodeToken used to silently eat tokens with an invalid type.
 func TestSimpleUseOfEncodeToken(t *testing.T) {
-	var buf bytes.Buffer
+	var buf strings.Builder
 	enc := NewEncoder(&buf)
 	if err := enc.EncodeToken(&StartElement{Name: Name{"", "object1"}}); err == nil {
 		t.Errorf("enc.EncodeToken: pointer type should be rejected")

src/encoding/xml/xml_test.go

@@ -894,7 +894,7 @@ func TestEscapeTextInvalidChar(t *testing.T) {
 	input := []byte("A \x00 terminated string.")
 	expected := "A \uFFFD terminated string."
 
-	buff := new(bytes.Buffer)
+	buff := new(strings.Builder)
 	if err := EscapeText(buff, input); err != nil {
 		t.Fatalf("have %v, want nil", err)
 	}