How to test python/flask app with third-party http lib?

Question

I have a purest suite for my flask app that works great. However, I want to test some of my code that uses a third-party library (Qt) to send http requests. How is this possible? I see flask-testing has the live_server fixture which accomplishes this along with flask.url_for(), but it takes too much time to start up the server in the fixture.

Is there a faster way to send an http request from a third-party http lib to a flask app?

Thanks!

Answer 1

Turns out you can do this by manually converting the third-party request to the FlaskClient request, using a monkeypatch for whatever "send" method the third-party lib uses, then convert the flask.Response response back to a third-party reply object. All this occurs without using a TCP port.

Here is the fixture I wrote to bridge Qt http requests to the flask app:

@pytest.fixture
def qnam(qApp, client, monkeypatch):

    def sendCustomRequest(request, verb, data):
        # Qt -> Flask
        headers = []
        for name in request.rawHeaderList():
            key = bytes(name).decode('utf-8')
            value = bytes(request.rawHeader(name)).decode('utf-8')
            headers.append((key, value))
        query_string = None
        if request.url().hasQuery():
            query_string = request.url().query()
        # method = request.attribute(QNetworkRequest.CustomVerbAttribute).decode('utf-8')
        # send
        response = FlaskClient.open(client,
                                    request.url().path(),
                                    method=verb.decode('utf-8'),
                                    headers=headers,
                                    data=data)
        # Flask -> Qt
        class NetworkReply(QNetworkReply):
            def abort(self):
                pass
        reply = NetworkReply()
        reply.setAttribute(QNetworkRequest.HttpStatusCodeAttribute, response.status_code)
        for key, value in response.headers:
            reply.setRawHeader(key.encode('utf-8'), value.encode('utf-8'))
        reply.open(QIODevice.ReadWrite)
        reply.write(response.data)
        QTimer.singleShot(10, reply.finished.emit) # after return
        return reply

    qnam = QNetworkAccessManager.instance() # or wherever you get your instance

    monkeypatch.setattr(qnam, 'sendCustomRequest', sendCustomRequest)
    return ret