go benchmark test

cat.go

package cat

import (
	"bytes"
)

func buf(ss []string) string {
	var b bytes.Buffer
	for _, s := range ss {
		b.WriteString(s)
	}
	return b.String()
}

cat_test.go

package cat

import (
	"strings"
	"testing"
)

func seed(n int) []string {
	s := make([]string, 0, n)
	for i := 0; i < n; i++ {
		s = append(s, "a")
	}
	return s
}

func BenchmarkBuf(b *testing.B) {
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		buf(seed(i * 10))
	}
}

func BenchmarkJoin(b *testing.B) {
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		strings.Join(seed(i*10), "")
	}
}

note.md

% go vet ./...
% go test -bench ./...
?   	_/Users/peketamin/ghq/github.com/peketamin/big-stones	[no test files]

↓

% go test ./... -bench .+
goos: darwin
goarch: amd64
BenchmarkHello-8   	24976813	        44.3 ns/op
PASS
ok  	_/Users/peketamin/ghq/github.com/peketamin/big-stones	1.212s
goos: darwin
goarch: amd64
BenchmarkBuf-8    	   10000	    645318 ns/op
BenchmarkJoin-8   	   10000	    716953 ns/op
PASS
ok  	_/Users/peketamin/ghq/github.com/peketamin/big-stones/cat	13.682s

terminal.sh

% tree .
.
├── README.md
├── cat
│   ├── cat.go
│   └── cat_test.go
├── chan
├── chan.go
└── chan_test.go