def METHOD_NAME(token_client, organizer, event):
    res = copy.copy(TEST_WEBHOOK_CREATE_PAYLOAD)
    res['target_url'] = 'foo.bar'
    resp = token_client.post(
        '/api/v1/organizers/{}/webhooks/'.format(organizer.slug),
        res,
        format='json'
    )
    assert resp.status_code == 400
    assert resp.data == {'target_url': ['Enter a valid URL.']}