benchmark different error creation methods

error_test.go

package main

import (
	"errors"
	"fmt"
	"strconv"
	"testing"
)

type MyError struct {
	Err  error
	File string
	Line int
	Msg  string
}

func (e MyError) Error() string {
	return e.File + ":" + strconv.Itoa(e.Line) + ": " + e.Msg + " -- " + e.Err.Error()
}

func newError(file string, line int, msg string, err error) error {
	return errors.New(file + ":" + strconv.Itoa(line) + ": " + msg + " -- " + err.Error())
}

func f(err error) {
	err.Error()
}

func BenchmarkErrorF(b *testing.B) {
	b.ReportAllocs()
	err := errors.New("base")

	for i := 0; i < 100000; i++ {
		f(fmt.Errorf("%s:%d: %s %v", "test.go", 1, "wrapped error", err))
	}
}

func BenchmarkErrorNew(b *testing.B) {
	b.ReportAllocs()
	err := errors.New("base")

	for i := 0; i < 100000; i++ {
		f(newError("test.go", 1, "wrapped error", err))
	}
}

func BenchmarkErrorCustom(b *testing.B) {
	b.ReportAllocs()
	err := errors.New("base")

	for i := 0; i < 100000; i++ {
		f(MyError{Err: err, File: "abc", Line: 1, Msg: "wrapped error"})
	}
}

/*
goos: darwin
goarch: amd64
BenchmarkErrorF-4        	1000000000	         0.03 ns/op	       0 B/op	       0 allocs/op
BenchmarkErrorNew-4      	2000000000	         0.00 ns/op	       0 B/op	       0 allocs/op
BenchmarkErrorCustom-4   	2000000000	         0.01 ns/op	       0 B/op	       0 allocs/op
PASS
ok  	_/private/tmp	0.316s
*/