def METHOD_NAME(self, mocker):
    mock_post = mocker.patch('requests.post')
    mock_user_model = mocker.patch('servicex.models.UserModel')
    secret = 'my-slack-secret'
    client = self._test_client(extra_config={'SLACK_SIGNING_SECRET': 'my-slack-secret'})
    timestamp = time.time()
    body = f"payload={quote_plus(json.dumps(payload), safe=',:@/')}"
    sig_basestring = f"v0:{timestamp}:{body}".encode('utf-8')
    signature = hmac.new(secret.encode('utf-8'), sig_basestring,
                         digestmod=hashlib.sha256).hexdigest()
    headers = {
        'X-Slack_Request-Timestamp': timestamp,
        'X-Slack-Signature': "v0=" + signature,
    }
    response: Response = client.post('/slack',
                                     data={'payload': json.dumps(payload)},
                                     headers=headers)
    assert response.status_code == 200
    email = payload['actions'][0]['value']
    assert mock_user_model.accept.called_once_with(email)
    with client.application.app_context():
        from servicex.web.slack_msg_builder import signup_ia
        resp = signup_ia(payload['message'], payload['user'], 'accept_user')
        assert mock_post.called_once_with(payload['response_url'], resp)