@Test
    public void testUnknownSigAlgOID() {
        ServiceTester.test("CertificateFactory")
            .withAlgorithm("X509")
            .run((p, algorithm) -> {
                X509Certificate c = certificateFromPEM(p, UNKNOWN_SIGNATURE_OID);
                assertEquals("1.2.840.113554.4.1.72585.2", c.getSigAlgOID());
                assertThrows(NoSuchAlgorithmException.class, () -> c.verify(c.getPublicKey()));
            });
    }
Confirm that explicit EC params aren't accepted in certificates.
common/src/test/java/org/conscrypt/java/security/cert/X509CertificateTest.java