How to get the super user in a functional test? How can I get the information for the super user (uid 1) in a functional test?

I want to test the external auth logic I have written, and one of the steps is authenticating the Drupal superuser locally instead of in the remote system. I am not seeing a way to get the username/password of that user in order to simulate a login.

Test:

  /**
   * The superuser should not authenticate to Netforum.
   */
  public function testSuperUserUsesDrupalAuthentication() {
    $this-&gt;drupalGet('user/login');
    $edit = ['name' =&gt; $this-&gt;rootUser-&gt;getEmail(), 'pass' =&gt; $this-&gt;rootUser-&gt;pass_raw];
    $this-&gt;drupalPostForm(NULL, $edit, t('Log in'));

    $user = \Drupal::currentUser();
    $this-&gt;assertEquals(1, $user-&gt;id());
  }
Looking into BrowserTestBase I accidentally found $this-&gt;rootUser-&gt;name and $this-&gt;rootUser-&gt;pass_raw last week. These are being used in installParameters(). I have not tested it, but I suppose you should be able to use those in other functions as well. 

rootUser appears to be a full AccountInterface object, so getName() and other methods should work as well..