code: func SetupCertificateAuthorithy(t *testing.T) (*x509.Certificate, crypto.Signer) {
  	caCert, caKey, err := pkiutil.NewCertificateAuthority(&certutil.Config{CommonName: "kubernetes"})
  	if err != nil {
  		t.Fatalf("failure while generating CA certificate and key: %v", err)
  	}
  
  	return caCert, caKey
  }
docs: // SetupCertificateAuthorithy is a utility function for kubeadm testing that creates a
  // CertificateAuthorithy cert/key pair