BasicAuth requires a user to log in before viewing an application.  We
create it with a dictionary of username:password

::

    >>> from basicauth import BasicAuth
    >>> from simpleapp import simple_app
    >>> wrapped_app = BasicAuth(simple_app, {'user': 'secret'})

Now when we try to access the application we will get a 401 response::

    >>> from testrunner import send_request
    >>> print send_request(wrapped_app, '/')
    401 Authorization Required
    Content-Type: text/plain
    Www-Authenticate: Basic realm="www"
    ...

But when we send the proper login information we will get through::

    >>> auth = 'Basic ' + 'user:secret'.encode('base64')
    >>> print send_request(wrapped_app, '/', 
    ...                    environ={'HTTP_AUTHORIZATION': auth})
    200 OK
    ...