@Test
  public void authenticateShouldReturnFailureMessageIfNullCredentials() throws Exception {
    props.setProperty(SECURITY_PEER_AUTHENTICATOR,
        AuthenticatorReturnsNulls.class.getName() + ".create");
    String result = authenticator.authenticate(member, null, props);
    assertThat(result).startsWith("Failed to find credentials from");
  }
Unit tests GMSAuthenticator using old security.
geode-core/src/test/java/org/apache/geode/distributed/internal/membership/adapter/auth/GMSAuthenticatorWithAuthenticatorTest.java