Add a test that checks whether 3 known subject attributes can be retrieved by NID

    assert_eq!(&cn as &str, "test_cert")

}

#[test]

fn test_nid_values() {

    let cert_path = Path::new("test/nid_test_cert.pem");

    let mut file = File::open(&cert_path)

        .ok()

        .expect("Failed to open `test/nid_test_cert.pem`");

    let cert = X509::from_pem(&mut file).ok().expect("Failed to load PEM");

    let subject = cert.subject_name();

    let cn = match subject.text_by_nid(Nid::CN) {

        Some(x) => x,

        None => panic!("Failed to read CN from cert")

    };

    assert_eq!(&cn as &str, "example.com");

    let email = match subject.text_by_nid(Nid::Email) {

        Some(x) => x,

        None => panic!("Failed to read subject email address from cert")

    };

    assert_eq!(&email as &str, "test@example.com");

    let friendly = match subject.text_by_nid(Nid::FriendlyName) {

        Some(x) => x,

        None => panic!("Failed to read subject friendly name from cert")

    };

    assert_eq!(&friendly as &str, "Example");

}

-----BEGIN CERTIFICATE-----

MIIB1DCCAX6gAwIBAgIJAMzXWZGWHleWMA0GCSqGSIb3DQEBCwUAMFYxHzAdBgkq

hkiG9w0BCQEWEHRlc3RAZXhhbXBsZS5jb20xFDASBgNVBAMMC2V4YW1wbGUuY29t

MR0wGwYJKoZIhvcNAQkUHg4ARQB4AGEAbQBwAGwAZTAeFw0xNTA3MDEwNjQ3NDRa

Fw0xNTA3MzEwNjQ3NDRaMFYxHzAdBgkqhkiG9w0BCQEWEHRlc3RAZXhhbXBsZS5j

b20xFDASBgNVBAMMC2V4YW1wbGUuY29tMR0wGwYJKoZIhvcNAQkUHg4ARQB4AGEA

bQBwAGwAZTBcMA0GCSqGSIb3DQEBAQUAA0sAMEgCQQCmejzp4+o35FD0hAnx2trL

08h07X5jZca9DgZH35hWXPh7fMucLt/IPXIRnz2zKEa/Mo6D2V/fx03Mqo0epid7

AgMBAAGjLzAtMB0GA1UdDgQWBBRQa57tXz3rZNRz+fTbo3w3jQJMBTAMBgNVHRME

BTADAQH/MA0GCSqGSIb3DQEBCwUAA0EAm0iY9cr+gvC+vcQIebdofpQ4GcDW8U6W

Bxs8ZXinLl69P0jYLum3+XITNFRiyQqcivaxdxthxDNOX7P+aKwkJA==

-----END CERTIFICATE-----