Fix bug when runes with width > 1 in an option with multiple lines (#445)

* Fix bug when runes with width > 1 in an option with multiple lines

* add test

Co-authored-by: Alec Aivazis <[email protected]>

Author: VCisHere

renderer.go

@@ -3,8 +3,6 @@ package survey
 import (
 	"bytes"
 	"fmt"
-	"unicode/utf8"
-
 	"github.com/AlecAivazis/survey/v2/core"
 	"github.com/AlecAivazis/survey/v2/terminal"
 	"golang.org/x/term"
@@ -180,7 +178,8 @@ func (r *Renderer) countLines(buf bytes.Buffer) int {
 			delim = len(bufBytes) // no new line found, read rest of text
 		}
 
-		if lineWidth := utf8.RuneCount(bufBytes[curr:delim]); lineWidth > w {
+		str := string(bufBytes[curr:delim])
+		if lineWidth := terminal.StringWidth(str); lineWidth > w {
 			// account for word wrapping
 			count += lineWidth / w
 			if (lineWidth % w) == 0 {

terminal/runereader.go

@@ -384,3 +384,12 @@ func runeWidth(r rune) int {
 	}
 	return 1
 }
+
+func StringWidth(str string) int {
+	w := 0
+	rs := []rune(str)
+	for _, r := range rs {
+		w += runeWidth(r)
+	}
+	return w
+}

tests/input.go

@@ -2,7 +2,7 @@ package main
 
 import (
 	"github.com/AlecAivazis/survey/v2"
-	"github.com/AlecAivazis/survey/v2/tests/util"
+	TestUtil "github.com/AlecAivazis/survey/v2/tests/util"
 )
 
 var val = ""
@@ -23,6 +23,8 @@ var table = []TestUtil.TestTableEntry{
 		"Delete and forward delete test at random location (test if screen overflows)", &survey.Input{Message: "Hello world"}, &val, nil,
 	}, {
 		"Moving around lines with left & right arrow keys", &survey.Input{Message: "Hello world"}, &val, nil,
+	}, {
+		"Runes with width > 1. Enter 一 you get to the next line", &survey.Input{Message: "Hello world"}, &val, nil,
 	},
 }