'Authenticates the FTP client using the test account.
@return: L{Deferred} of command response'

def _userLogin(self):

    d = self.assertCommandResponse(('USER    %s' % self.username), [('331    Password    required    for    %s.' % self.username)])
    return self.assertCommandResponse(('PASS    %s' % self.password), ['230    User    logged    in,    proceed'], chainDeferred=d)
