func startTestSocketPeer(t testing.TB, conn Conn, op string, chunkSize, totalSize int) (func(t testing.TB), error) {
	t.Helper()

	if runtime.GOOS == "windows" {
		// TODO(panjf2000): Windows has not yet implemented FileConn,
		//		remove this when it's implemented in https://go.dev/issues/9503.
		t.Fatalf("startTestSocketPeer is not supported on %s", runtime.GOOS)
	}

	f, err := conn.(interface{ File() (*os.File, error) }).File()

		b.Fatalf("expected %d copied bytes, but got %d", dataSize, n)
	}

	cancel()
}

func BenchmarkSendFile(b *testing.B) {
	if runtime.GOOS == "windows" {
		// TODO(panjf2000): Windows has not yet implemented FileConn,
		//		remove this when it's implemented in https://go.dev/issues/9503.
		b.Skipf("skipping on %s", runtime.GOOS)
	}

	b.Run("file-to-tcp", func(b *testing.B) { benchmarkSendFile(b, "tcp") })