A simple example of benchmarking with Go

main.go

package main

import (
	"bytes"
	"math/rand"
	"strings"
)

func main() {
	// This main function does nothing since we only want to test benchmarking
}

func UseConcatOperator(slice []string) string {
	var s string
	for _, val := range slice {
		s = s + val
	}
	return s
}

func UseBytesBuffer(slice []string) string {
	var b bytes.Buffer
	for _, val := range slice {
		b.WriteString(val)
	}
	return b.String()
}

func UseStringsBuilder(slice []string) string {
	var sb strings.Builder
	for _, val := range slice {
		sb.WriteString(val)
	}
	return sb.String()
}

func GetSliceOfStrings() []string {
	size := 1000
	slice := make([]string, size)
	for i := 0; i < size; i++ {
		s := "abcdedfghijklmnopqrstuvwxyz"
		slice[i] = s
	}
	return slice
}

func GetRandomSliceOfStrings() []string {
	size := 1000
	slice := make([]string, size)
	for i := 0; i < size; i++ {
		s := GenerateRandomLowercase()
		slice[i] = s
	}
	return slice
}

func GenerateRandomLowercase() string {
	// Randomize only lowercase
	charSet := "abcdedfghijklmnopqrstuvwxyz"
	var out strings.Builder
	length := 15
	for i := 0; i < length; i++ {
		random := rand.Intn(len(charSet))
		randomChar := charSet[random]
		out.WriteString(string(randomChar))
	}
	return out.String()
}

main_test.go

package main

import (
	"testing"
)

var slice = GetSliceOfStrings()

func BenchmarkUseConcatOperator(b *testing.B) {
	for i := 0; i < b.N; i++ {
		UseConcatOperator(slice)
	}
}

func BenchmarkUseBytesBuffer(b *testing.B) {
	for i := 0; i < b.N; i++ {
		UseBytesBuffer(slice)
	}
}

func BenchmarkUseStringsBuilder(b *testing.B) {
	for i := 0; i < b.N; i++ {
		UseStringsBuilder(slice)
	}
}