src/third_party/web_platform_tests/XMLHttpRequest/send-authentication-prompt-2-manual.htm

<!doctype html>
<html>
  <head>
    <title>XMLHttpRequest: WWW-Authenticate challenge when user,pass are not passed to open()</title>
    <script src="/resources/testharness.js"></script>
    <script src="/resources/testharnessreport.js"></script>
    <link rel="help" href="https://xhr.spec.whatwg.org/#the-send()-method" data-tested-assertations="following::code[contains(@title,'http-authorization')]/.." />
  </head>
  <body>
    <p>Please follow these steps to complete the test:</p>
    <ol>
      <li>If you are prompted for user name and password, type in 'usr' and 'secret'</li>
    </ol>
    <div id="log"></div>
    <script>
      test(function() {
        var client = new XMLHttpRequest(),
          urlstart = location.host + location.pathname.replace(/\/[^\/]*$/, '/')
        client.open("GET", location.protocol+'//'+urlstart + "resources/auth6/auth.py", false)
        client.send(null)
        assert_equals(client.responseText, 'usr' + "\n" + 'secret')
      }, document.title)
    </script>
  </body>
</html>