[Golang] Get UTF-8 String Width

package mylib

import "golang.org/x/text/width"

func GetWidthUTF8String(s string) int {
	size := 0
	for _, runeValue := range s {
		p := width.LookupRune(runeValue)
		if p.Kind() == width.EastAsianWide {
			size += 2
			continue
		}
		if p.Kind() == width.EastAsianNarrow {
			size += 1
			continue
		}
		panic("cannot determine!")
	}
	return size
}

package mylib

import "testing"

func TestGetWidthUTF8String(t *testing.T) {
	if GetWidthUTF8String("s: 你好") != 7 {
		t.Error("s: 你好")
	}
	if GetWidthUTF8String("s --asji勿勿") != 12 {
		t.Error("s --asji勿勿")
	}
}