### Question:
CertificateAuthority implements Authority { @Override public String getAuthenticateChallenge() { return ATHENZ_AUTH_CHALLENGE; }  @Override void initialize(); @Override String getID(); @Override String getDomain(); @Override String getHeader(); @Override String getAuthenticateChallenge(); @Override Principal authenticate(String creds, String remoteAddr, String httpMethod, StringBuilder errMsg); @Override CredSource getCredSource(); @Override Principal authenticate(X509Certificate[] certs, StringBuilder errMsg);  }### Answer:
@Test public void testGetAuthenticateChallenge() { CertificateAuthority authority = new CertificateAuthority(); assertEquals(authority.getAuthenticateChallenge(), "AthenzX509Certificate realm=\"athenz\""); }