def METHOD_NAME(self):
    clientapp.cfg.PRE_SELECTED_PROVIDER = False
    headers = {'Content-type': 'application/json'}
    data = {'provider_id': 'whatever'}
    json_data = json.dumps(data)
    self.client.post(url_for('configuration'),
                     data=json_data,
                     headers=headers)
    self.assertTrue(clientapp.cfg.PRE_SELECTED_PROVIDER, )