`fmt.Sprintf("%s", buf)` vs `string(buf)` for simple []byte arrays

README.md

Curiosity on the differences from moby/moby#16531 (comment)

$ go test
PASS
ok      _/home/vbatts/tmp/string        0.003s
$ go test -run=NONE -bench=. -test.benchmem=true 
PASS
BenchmarkString-4         100000             18982 ns/op               0 B/op          0 allocs/op
BenchmarkFmt-4              5000            248974 ns/op           48012 B/op       2000 allocs/op
ok      _/home/vbatts/tmp/string        3.369s

string_test.go

package str

import (
    "crypto/rand"
    "fmt"
    "log"
    "testing"
)

var randoList [1000][]byte

func init() {
    for i := 0; i < 1000; i++ {
        buf := make([]byte, 5)
        if _, err := rand.Read(buf); err != nil {
                log.Fatalf("failed init: %s", err)
        }
        randoList[i] = buf
    }
}

func TestFormatting(t *testing.T) {
    for i, blob := range randoList {
        formatFmt := fmt.Sprintf("%s", blob)
        formatStr := string(blob)
        if formatFmt != formatStr {
                t.Errorf("%d: %q and %q do not match", i, formatFmt, formatStr)
        }
    }
}

func BenchmarkString(b *testing.B) {
    for i := 0; i < b.N; i++ {
        for _, blob := range randoList {
                _ = string(blob)
        }
    }
}

func BenchmarkFmt(b *testing.B) {
    for i := 0; i < b.N; i++ {
        for _, blob := range randoList {
                _ = fmt.Sprintf("%s", blob)
        }
    }
}