erface, or an HTTP handler that emits internal statistics.
                                    </p>
                                </dd>
                                
                                <dd>
                                    <p>
                                        <a data-type="indexterm" data-primary="black-box monitoring" id="id-zdCxSrSgTWIdhb"></a>Testing externally visible behavior as a user would see it.
                                    </p>
                                </d