foo_test.go

package foo

import (
	"testing"
)

type comment struct {
	ID int
}

var (
	comments []comment
)

func ready() {
	comments = make([]comment, 60000)
	for i := 0; i < len(comments); i++ {
		comments[i].ID = i
	}
}

func BenchmarkTest1(b *testing.B) {
	ready()

	b.ResetTimer()
	hoge := []int{}
	for _, comment := range comments {
		hoge = append([]int{comment.ID}, hoge...)
	}
}

func BenchmarkTest2(b *testing.B) {
	ready()

	b.ResetTimer()
	hoge := make([]int, len(comments))
	l := len(comments)
	for i := l - 1; i >= 0; i-- {
		hoge[i] = comments[i].ID
	}
}

gistfile1.txt

testing: warning: no tests to run
PASS
BenchmarkTest1-4               1        11059105800 ns/op
BenchmarkTest2-4        2000000000               0.00 ns/op
ok      _/c_/dev/arrr   11.519s