cert, err := ParseCertificate(pemBlock.Bytes)
	if err != nil {
		t.Fatalf("failed to parse certificate: %s", err)
	}
	if sa := cert.SignatureAlgorithm; sa != ECDSAWithSHA1 {
		t.Errorf("signature algorithm is %v, want %v", sa, ECDSAWithSHA1)
	}
	if err = cert.CheckSignatureFrom(cert); err == nil {
		t.Fatalf("certificate verification succeeded incorrectly")
	}
	if _, ok := err.(InsecureAlgorithmError); !ok {