remove QuoteCharacter option

This seems to be one of the most reported issues, as it makes it a lot
harder to safely escape strings.

This option is very much an edge case, and it's causing too much issues
compared to what it provide.

text_formatter.go

@@ -52,10 +52,6 @@ type TextFormatter struct {
 	// QuoteEmptyFields will wrap empty fields in quotes if true
 	QuoteEmptyFields bool
 
-	// QuoteCharacter can be set to the override the default quoting character "
-	// with something else. For example: ', or `.
-	QuoteCharacter string
-
 	// Whether the logger's out is to a terminal
 	isTerminal bool
 
@@ -63,9 +59,6 @@ type TextFormatter struct {
 }
 
 func (f *TextFormatter) init(entry *Entry) {
-	if len(f.QuoteCharacter) == 0 {
-		f.QuoteCharacter = "\""
-	}
 	if entry.Logger != nil {
 		f.isTerminal = IsTerminal(entry.Logger.Out)
 	}
@@ -177,13 +170,6 @@ func (f *TextFormatter) appendValue(b *bytes.Buffer, value interface{}) {
 	if !f.needsQuoting(stringVal) {
 		b.WriteString(stringVal)
 	} else {
-		b.WriteString(f.quoteString(stringVal))
+		b.WriteString(fmt.Sprintf("%q", stringVal))
 	}
 }
-
-func (f *TextFormatter) quoteString(v string) string {
-	escapedQuote := fmt.Sprintf("\\%s", f.QuoteCharacter)
-	escapedValue := strings.Replace(v, f.QuoteCharacter, escapedQuote, -1)
-
-	return fmt.Sprintf("%s%v%s", f.QuoteCharacter, escapedValue, f.QuoteCharacter)
-}

text_formatter_test.go

@@ -3,10 +3,10 @@ package logrus
 import (
 	"bytes"
 	"errors"
+	"fmt"
 	"strings"
 	"testing"
 	"time"
-	"fmt"
 )
 
 func TestQuoting(t *testing.T) {
@@ -15,7 +15,7 @@ func TestQuoting(t *testing.T) {
 	checkQuoting := func(q bool, value interface{}) {
 		b, _ := tf.Format(WithField("test", value))
 		idx := bytes.Index(b, ([]byte)("test="))
-		cont := bytes.Contains(b[idx+5:], []byte(tf.QuoteCharacter))
+		cont := bytes.Contains(b[idx+5:], []byte("\""))
 		if cont != q {
 			if q {
 				t.Errorf("quoting expected for: %#v", value)
@@ -41,23 +41,6 @@ func TestQuoting(t *testing.T) {
 	checkQuoting(false, errors.New("invalid"))
 	checkQuoting(true, errors.New("invalid argument"))
 
-	// Test for custom quote character.
-	tf.QuoteCharacter = "`"
-	checkQuoting(false, "")
-	checkQuoting(false, "abcd")
-	checkQuoting(false, "/foobar")
-	checkQuoting(false, "foo_bar")
-	checkQuoting(false, "foo@bar")
-	checkQuoting(false, "foobar^")
-	checkQuoting(true, "foobar$")
-	checkQuoting(true, "&foobar")
-	checkQuoting(true, errors.New("invalid argument"))
-
-	// Test for multi-character quotes.
-	tf.QuoteCharacter = "§~±"
-	checkQuoting(false, "abcd")
-	checkQuoting(true, errors.New("invalid argument"))
-
 	// Test for quoting empty fields.
 	tf.QuoteEmptyFields = true
 	checkQuoting(true, "")
@@ -65,7 +48,7 @@ func TestQuoting(t *testing.T) {
 	checkQuoting(true, errors.New("invalid argument"))
 }
 
-func TestEscaping_DefaultQuoteCharacter(t *testing.T) {
+func TestEscaping(t *testing.T) {
 	tf := &TextFormatter{DisableColors: true}
 
 	testCases := []struct {
@@ -105,35 +88,13 @@ func TestEscaping_Interface(t *testing.T) {
 	}
 }
 
-func TestEscaping_CustomQuoteCharacter(t *testing.T) {
-	tf := &TextFormatter{DisableColors: true}
-
-	testCases := []struct {
-		value     string
-		expected  string
-		quoteChar string
-	}{
-		{`ba"r`, `ba"r`, `'`},
-		{`ba'r`, `ba\'r`, `'`},
-		{`ba'r`, `ba'r`, `^`},
-	}
-
-	for _, tc := range testCases {
-		tf.QuoteCharacter = tc.quoteChar
-		b, _ := tf.Format(WithField("test", tc.value))
-		if !bytes.Contains(b, []byte(tc.expected)) {
-			t.Errorf("escaping expected for %q (result was %q instead of %q)", tc.value, string(b), tc.expected)
-		}
-	}
-}
-
 func TestTimestampFormat(t *testing.T) {
 	checkTimeStr := func(format string) {
 		customFormatter := &TextFormatter{DisableColors: true, TimestampFormat: format}
 		customStr, _ := customFormatter.Format(WithField("test", "test"))
 		timeStart := bytes.Index(customStr, ([]byte)("time="))
 		timeEnd := bytes.Index(customStr, ([]byte)("level="))
-		timeStr := customStr[timeStart+5+len(customFormatter.QuoteCharacter) : timeEnd-1-len(customFormatter.QuoteCharacter)]
+		timeStr := customStr[timeStart+5+len("\"") : timeEnd-1-len("\"")]
 		if format == "" {
 			format = time.RFC3339
 		}