for i := 0; i < num; i++ {
		l[i] = s
	}
	return strings.Join(l, "")
}

func newCSRPEM(t *testing.T) []byte {
	template := &x509.CertificateRequest{
		Subject: pkix.Name{
			Organization: []string{"testing-org"},
		},
	}

	_, key, err := ed25519.GenerateKey(rand.Reader)
	if err != nil {
		t.Fatal(err)
	}

	csrDER, err := x509.CreateCertificateRequest(rand.Reader, template, key)

==== Forward compatibility

	if err != nil {
		return nil, nil, fmt.Errorf("failed to generate serial number: %w", err)
	}

	template := x509.Certificate{
		SerialNumber: serialNumber,
		Subject: pkix.Name{
			Organization: []string{"Acme Co"},
		},
		NotBefore: notBefore,
		NotAfter:  notAfter,

		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,