func WritePKIFiles(t *testing.T, dir string, files PKIFiles) {
	for filename, body := range files {
		switch body := body.(type) {
		case *x509.Certificate:
			if err := certutil.WriteCert(filepath.Join(dir, filename), pkiutil.EncodeCertPEM(body)); err != nil {
				t.Errorf("unable to write certificate to file %q: [%v]", dir, err)
			}
		case *rsa.PublicKey: