The low-level networking protocol negotiation is all handled internally by Qt, and we can easily get connected to the outside world via the QNetworkAccessManager class. To be able to access this functionality, we need to add the network module to cm-lib.pro:

QT += sql network

One of Qt's weaknesses is the lack of interfaces, making unit testing difficult in some cases. If we just use QNetworkAccessManager directly, we won’t be able to test our code without making real calls to the network, which is undesirable. However, a quick and easy solution to this problem is to hide the Qt implementation behind an interface of our own, and we will do that here.

For the purposes of this chapter, all we need to be able to do with the network is check that we have connectivity and send a HTTP GET request. With this in mind, create a header file i-network-access-manager...