automated tests as a user?

I checked out (with svn) the code for Automated Testing. However, I want to run unit tests as a specific user.

Is there a way to do that? That is, is there a way to loggin with php code alone?

$user_id = $this->_make_user('author', 'user_login_name', 'password', 'test@test.com');
wp_set_current_user( $user_id );

as long as the class that you define the testcase in inherits from WPTestCase, then you can use the _make_user function. The function is found in this svn repository, and is defined in wp-testlib/base.php line 380.

NEW:

I switched to using wp_insert_user.

the following is in my setUp:

    $this->user_id = wp_insert_user(array('user_login'=>'test_administrator', 'role'=>'administrator'));
    wp_set_current_user( $this->user_id , '');

and the following is in my teardown:

    wp_delete_user($this->user_id);
    $this->user_id = 0;