def METHOD_NAME(self):
    url = '/users/account'
    data = {
        'currentpassword': self.global_passwords['contributor'],
        'forum_username': 'unique'
    }
    self.post_json_with_contributor(url, data, status=200)
    data = {
        'currentpassword': self.global_passwords['contributor2'],
        'forum_username': 'Unique'
    }
    json = self.post_json_with_contributor(url,
                                           data,
                                           status=400,
                                           username='contributor2')
    self.assertEqual(json['errors'][0]['description'],
                     'Already used forum name')